diff --git a/imgui.cpp b/imgui.cpp
index 5a725c9..ca13fcd 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -214,6 +214,8 @@
  Here is a change-log of API breaking changes, if you are using one of the functions listed, expect to have to fix some code.
  Also read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2017/11/18 (1.53) - Style, Begin: removed ImGuiWindowFlags_ShowBorders window flag. Borders are now fully set up in the ImGuiStyle structure (see e.g. style.FrameBorderSize, style.WindowBorderSize). Use ImGui::ShowStyleEditor() to look them up.
+                       Please note that the style system will keep evolving (hopefully stabilizing in Q1 2018), and so custom styles will probably subtly break over time. It is recommended you use the StyleColorsClassic(), StyleColorsDark(), StyleColorsLight() functions.
  - 2017/11/18 (1.53) - Style: removed ImGuiCol_ComboBg in favor of combo boxes using ImGuiCol_PopupBg for consistency.
  - 2017/11/18 (1.53) - Style: renamed ImGuiCol_ChildWindowBg to ImGuiCol_ChildBg.
  - 2017/11/18 (1.53) - Style: renamed style.ChildWindowRounding to style.ChildRounding, ImGuiStyleVar_ChildWindowRounding to ImGuiStyleVar_ChildRounding.
@@ -704,12 +706,16 @@
     Alpha                   = 1.0f;             // Global alpha applies to everything in ImGui
     WindowPadding           = ImVec2(8,8);      // Padding within a window
     WindowRounding          = 9.0f;             // Radius of window corners rounding. Set to 0.0f to have rectangular windows
+    WindowBorderSize        = 0.0f;             // Thickness of border around windows. Generally set to 0.0f or 1.0f. Other values not well tested.
     WindowMinSize           = ImVec2(32,32);    // Minimum window size
     WindowTitleAlign        = ImVec2(0.0f,0.5f);// Alignment for title bar text
     ChildRounding           = 0.0f;             // Radius of child window corners rounding. Set to 0.0f to have rectangular child windows
+    ChildBorderSize         = 1.0f;             // Thickness of border around child windows. Generally set to 0.0f or 1.0f. Other values not well tested.
     PopupRounding           = 0.0f;             // Radius of popup window corners rounding. Set to 0.0f to have rectangular child windows
+    PopupBorderSize         = 1.0f;             // Thickness of border around popup or tooltip windows. Generally set to 0.0f or 1.0f. Other values not well tested.
     FramePadding            = ImVec2(4,3);      // Padding within a framed rectangle (used by most widgets)
     FrameRounding           = 0.0f;             // Radius of frame corners rounding. Set to 0.0f to have rectangular frames (used by most widgets).
+    FrameBorderSize         = 0.0f;             // Thickness of border around frames. Generally set to 0.0f or 1.0f. Other values not well tested.
     ItemSpacing             = ImVec2(8,4);      // Horizontal and vertical spacing between widgets/lines
     ItemInnerSpacing        = ImVec2(4,4);      // Horizontal and vertical spacing between within elements of a composed widget (e.g. a slider and its label)
     TouchExtraPadding       = ImVec2(0,0);      // Expand reactive bounding box for touch-based system where touch position is not accurate enough. Unfortunately we don't sort widgets so priority on overlap will always be given to the first widget. So don't grow this too much!
@@ -3075,10 +3081,11 @@
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
     window->DrawList->AddRectFilled(p_min, p_max, fill_col, rounding);
-    if (border && (window->Flags & ImGuiWindowFlags_ShowBorders))
+    const float border_size = g.Style.FrameBorderSize;
+    if (border && border_size > 0.0f)
     {
-        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding);
-        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding);
+        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding, ~0, border_size);
+        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding, ~0, border_size);
     }
 }
 
@@ -3086,10 +3093,11 @@
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
-    if (window->Flags & ImGuiWindowFlags_ShowBorders)
+    const float border_size = g.Style.FrameBorderSize;
+    if (border_size > 0.0f)
     {
-        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding);
-        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding);
+        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding, ~0, border_size);
+        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding, ~0, border_size);
     }
 }
 
@@ -3665,14 +3673,12 @@
 bool ImGui::BeginPopupEx(ImGuiID id, ImGuiWindowFlags extra_flags)
 {
     ImGuiContext& g = *GImGui;
-    ImGuiWindow* window = g.CurrentWindow;
     if (!IsPopupOpen(id))
     {
         ClearSetNextWindowData(); // We behave like Begin() and need to consume those values
         return false;
     }
 
-    PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
     ImGuiWindowFlags flags = extra_flags|ImGuiWindowFlags_Popup|ImGuiWindowFlags_NoTitleBar|ImGuiWindowFlags_NoResize|ImGuiWindowFlags_NoSavedSettings;
 
     char name[20];
@@ -3682,9 +3688,7 @@
         ImFormatString(name, IM_ARRAYSIZE(name), "##popup_%08x", id); // Not recycling, so we can close/open during the same frame
 
     bool is_open = Begin(name, NULL, flags);
-    if (!(window->Flags & ImGuiWindowFlags_ShowBorders))
-        g.CurrentWindow->Flags &= ~ImGuiWindowFlags_ShowBorders;
-    if (!is_open) // NB: is_open can be 'false' when the popup is completely clipped (e.g. zero size display)
+    if (!is_open) // NB: Begin can return false when the popup is completely clipped (e.g. zero size display)
         EndPopup();
 
     return is_open;
@@ -3698,7 +3702,7 @@
         ClearSetNextWindowData(); // We behave like Begin() and need to consume those values
         return false;
     }
-    return BeginPopupEx(g.CurrentWindow->GetID(str_id), ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(g.CurrentWindow->GetID(str_id), ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 bool ImGui::IsPopupOpen(ImGuiID id)
@@ -3747,8 +3751,6 @@
     IM_ASSERT(window->Flags & ImGuiWindowFlags_Popup);  // Mismatched BeginPopup()/EndPopup() calls
     IM_ASSERT(GImGui->CurrentPopupStack.Size > 0);
     End();
-    if (!(window->Flags & ImGuiWindowFlags_Modal))
-        PopStyleVar();
 }
 
 bool ImGui::OpenPopupOnItemClick(const char* str_id, int mouse_button)
@@ -3774,7 +3776,7 @@
     IM_ASSERT(id != 0);                                                  // However, you cannot pass a NULL str_id if the last item has no identifier (e.g. a Text() item)
     if (IsMouseClicked(mouse_button) && IsItemHovered(ImGuiHoveredFlags_AllowWhenBlockedByPopup))
         OpenPopupEx(id, true);
-    return BeginPopupEx(id, ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(id, ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 bool ImGui::BeginPopupContextWindow(const char* str_id, int mouse_button, bool also_over_items)
@@ -3786,7 +3788,7 @@
         if (IsWindowHovered(ImGuiHoveredFlags_AllowWhenBlockedByPopup))
             if (also_over_items || !IsAnyItemHovered())
                 OpenPopupEx(id, true);
-    return BeginPopupEx(id, ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(id, ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 bool ImGui::BeginPopupContextVoid(const char* str_id, int mouse_button)
@@ -3796,11 +3798,12 @@
     ImGuiID id = GImGui->CurrentWindow->GetID(str_id);
     if (!IsAnyWindowHovered() && IsMouseClicked(mouse_button))
         OpenPopupEx(id, true);
-    return BeginPopupEx(id, ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(id, ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 static bool BeginChildEx(const char* name, ImGuiID id, const ImVec2& size_arg, bool border, ImGuiWindowFlags extra_flags)
 {
+    ImGuiContext& g = *GImGui;
     ImGuiWindow* parent_window = ImGui::GetCurrentWindow();
     ImGuiWindowFlags flags = ImGuiWindowFlags_NoTitleBar|ImGuiWindowFlags_NoResize|ImGuiWindowFlags_NoSavedSettings|ImGuiWindowFlags_ChildWindow;
     flags |= (parent_window->Flags & ImGuiWindowFlags_NoMove);  // Inherit the NoMove flag
@@ -3812,8 +3815,10 @@
         size.x = ImMax(content_avail.x, 4.0f) - fabsf(size.x); // Arbitrary minimum zero-ish child size of 4.0f (0.0f causing too much issues)
     if (size.y <= 0.0f)
         size.y = ImMax(content_avail.y, 4.0f) - fabsf(size.y);
-    if (border)
-        flags |= ImGuiWindowFlags_ShowBorders;
+
+    const float backup_border_size = g.Style.ChildBorderSize;
+    if (!border)
+        g.Style.ChildBorderSize = 0.0f;
     flags |= extra_flags;
 
     char title[256];
@@ -3826,8 +3831,7 @@
     bool ret = ImGui::Begin(title, NULL, flags);
     ImGuiWindow* child_window = ImGui::GetCurrentWindow();
     child_window->AutoFitChildAxises = auto_fit_axises;
-    if (!(parent_window->Flags & ImGuiWindowFlags_ShowBorders))
-        child_window->Flags &= ~ImGuiWindowFlags_ShowBorders;
+    g.Style.ChildBorderSize = backup_border_size;
 
     return ret;
 }
@@ -3876,14 +3880,15 @@
     const ImGuiStyle& style = g.Style;
     PushStyleColor(ImGuiCol_ChildBg, style.Colors[ImGuiCol_FrameBg]);
     PushStyleVar(ImGuiStyleVar_ChildRounding, style.FrameRounding);
+    PushStyleVar(ImGuiStyleVar_ChildBorderSize, style.FrameBorderSize);
     PushStyleVar(ImGuiStyleVar_WindowPadding, style.FramePadding);
-    return BeginChild(id, size, (g.CurrentWindow->Flags & ImGuiWindowFlags_ShowBorders) ? true : false, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_AlwaysUseWindowPadding | extra_flags);
+    return BeginChild(id, size, true, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_AlwaysUseWindowPadding | extra_flags);
 }
 
 void ImGui::EndChildFrame()
 {
     EndChild();
-    PopStyleVar(2);
+    PopStyleVar(3);
     PopStyleColor();
 }
 
@@ -4265,13 +4270,15 @@
             }
         }
 
-        // Lock window padding so that altering the ShowBorders flag for children doesn't have side-effects.
+        // Lock window padding so that altering the border sizes for children doesn't have side-effects.
         window->WindowPadding = style.WindowPadding;
-        if ((flags & ImGuiWindowFlags_ChildWindow) && !(flags & (ImGuiWindowFlags_AlwaysUseWindowPadding | ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_ComboBox | ImGuiWindowFlags_Popup)))
+        if ((flags & ImGuiWindowFlags_ChildWindow) && !(flags & (ImGuiWindowFlags_AlwaysUseWindowPadding | ImGuiWindowFlags_ComboBox | ImGuiWindowFlags_Popup)) && style.WindowBorderSize == 0.0f)
             window->WindowPadding = ImVec2(0.0f, (flags & ImGuiWindowFlags_MenuBar) ? style.WindowPadding.y : 0.0f);
-        window->WindowBorderSize = (flags & ImGuiWindowFlags_ShowBorders) ? 1.0f : 0.0f;
         window->WindowRounding = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildRounding : ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupRounding : style.WindowRounding;
+        window->WindowBorderSize = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildBorderSize : ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupBorderSize : style.WindowBorderSize;
+        const ImVec2 window_padding = window->WindowPadding;
         const float window_rounding = window->WindowRounding;
+        const float window_border_size = window->WindowBorderSize;
 
         // Calculate auto-fit size, handle automatic resize
         const ImVec2 size_auto_fit = CalcSizeAutoFit(window);
@@ -4405,7 +4412,10 @@
         if (window->Collapsed)
         {
             // Title bar only
+            float backup_border_size = style.FrameBorderSize;
+            g.Style.FrameBorderSize = window->WindowBorderSize;
             RenderFrame(title_bar_rect.Min, title_bar_rect.Max, GetColorU32(ImGuiCol_TitleBgCollapsed), true, window_rounding);
+            g.Style.FrameBorderSize = backup_border_size;
         }
         else
         {
@@ -4459,9 +4469,9 @@
             if (flags & ImGuiWindowFlags_MenuBar)
             {
                 ImRect menu_bar_rect = window->MenuBarRect();
-                if (flags & ImGuiWindowFlags_ShowBorders)
-                    window->DrawList->AddLine(menu_bar_rect.GetBL(), menu_bar_rect.GetBR(), GetColorU32(ImGuiCol_Border));
                 window->DrawList->AddRectFilled(menu_bar_rect.GetTL(), menu_bar_rect.GetBR(), GetColorU32(ImGuiCol_MenuBarBg), (flags & ImGuiWindowFlags_NoTitleBar) ? window_rounding : 0.0f, ImGuiCorner_TopLeft|ImGuiCorner_TopRight);
+                if (style.FrameBorderSize > 0.0f)
+                    window->DrawList->AddLine(menu_bar_rect.GetBL(), menu_bar_rect.GetBR(), GetColorU32(ImGuiCol_Border), style.FrameBorderSize);
             }
 
             // Scrollbars
@@ -4475,20 +4485,17 @@
             if (!(flags & ImGuiWindowFlags_NoResize))
             {
                 const ImVec2 br = window->Rect().GetBR();
-                window->DrawList->PathLineTo(br + ImVec2(-resize_corner_size, -window->WindowBorderSize));
-                window->DrawList->PathLineTo(br + ImVec2(-window->WindowBorderSize, -resize_corner_size));
-                window->DrawList->PathArcToFast(ImVec2(br.x - window_rounding - window->WindowBorderSize, br.y - window_rounding - window->WindowBorderSize), window_rounding, 0, 3);
+                window->DrawList->PathLineTo(br + ImVec2(-resize_corner_size, -window_border_size));
+                window->DrawList->PathLineTo(br + ImVec2(-window_border_size, -resize_corner_size));
+                window->DrawList->PathArcToFast(ImVec2(br.x - window_rounding - window_border_size, br.y - window_rounding - window_border_size), window_rounding, 0, 3);
                 window->DrawList->PathFillConvex(resize_col);
             }
 
             // Borders
-            if (flags & ImGuiWindowFlags_ShowBorders)
-            {
-                window->DrawList->AddRect(window->Pos+ImVec2(1,1), window->Pos+window->Size+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), window_rounding);
-                window->DrawList->AddRect(window->Pos, window->Pos+window->Size, GetColorU32(ImGuiCol_Border), window_rounding);
-                if (!(flags & ImGuiWindowFlags_NoTitleBar))
-                    window->DrawList->AddLine(title_bar_rect.GetBL()+ImVec2(1,0), title_bar_rect.GetBR()-ImVec2(1,0), GetColorU32(ImGuiCol_Border));
-            }
+            if (window_border_size > 0.0f)
+                window->DrawList->AddRect(window->Pos, window->Pos+window->Size, GetColorU32(ImGuiCol_Border), window_rounding, ~0, window_border_size);
+            if (style.FrameBorderSize > 0 && !(flags & ImGuiWindowFlags_NoTitleBar))
+                window->DrawList->AddLine(title_bar_rect.GetBL()+ImVec2(1,-1), title_bar_rect.GetBR()+ImVec2(-1,-1), GetColorU32(ImGuiCol_Border), style.FrameBorderSize);
         }
 
         // Update ContentsRegionMax. All the variable it depends on are set above in this function.
@@ -5042,11 +5049,15 @@
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, Alpha) },                // ImGuiStyleVar_Alpha
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, WindowPadding) },        // ImGuiStyleVar_WindowPadding
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, WindowRounding) },       // ImGuiStyleVar_WindowRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, WindowBorderSize) },     // ImGuiStyleVar_WindowBorderSize
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, WindowMinSize) },        // ImGuiStyleVar_WindowMinSize
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, ChildRounding) },        // ImGuiStyleVar_ChildRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, ChildBorderSize) },      // ImGuiStyleVar_ChildBorderSize
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, PopupRounding) },        // ImGuiStyleVar_PopupRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, PopupBorderSize) },      // ImGuiStyleVar_PopupBorderSize
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, FramePadding) },         // ImGuiStyleVar_FramePadding
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, FrameRounding) },        // ImGuiStyleVar_FrameRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, FrameBorderSize) },      // ImGuiStyleVar_FrameBorderSize
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, ItemSpacing) },          // ImGuiStyleVar_ItemSpacing
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, ItemInnerSpacing) },     // ImGuiStyleVar_ItemInnerSpacing
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, IndentSpacing) },        // ImGuiStyleVar_IndentSpacing
@@ -7619,7 +7630,7 @@
     // Render
     fraction = ImSaturate(fraction);
     RenderFrame(bb.Min, bb.Max, GetColorU32(ImGuiCol_FrameBg), true, style.FrameRounding);
-    bb.Expand(ImVec2(-window->WindowBorderSize, -window->WindowBorderSize));
+    bb.Expand(ImVec2(-style.FrameBorderSize, -style.FrameBorderSize));
     const ImVec2 fill_br = ImVec2(ImLerp(bb.Min.x, bb.Max.x, fraction), bb.Max.y);
     RenderRectFilledRangeH(window->DrawList, bb, GetColorU32(ImGuiCol_PlotHistogram), 0.0f, fraction, style.FrameRounding);
 
@@ -7742,10 +7753,10 @@
         window->DrawList->AddCircleFilled(center, radius-pad, GetColorU32(ImGuiCol_CheckMark), 16);
     }
 
-    if (window->Flags & ImGuiWindowFlags_ShowBorders)
+    if (style.FrameBorderSize > 0.0f)
     {
-        window->DrawList->AddCircle(center+ImVec2(1,1), radius, GetColorU32(ImGuiCol_BorderShadow), 16);
-        window->DrawList->AddCircle(center, radius, GetColorU32(ImGuiCol_Border), 16);
+        window->DrawList->AddCircle(center+ImVec2(1,1), radius, GetColorU32(ImGuiCol_BorderShadow), 16, style.FrameBorderSize);
+        window->DrawList->AddCircle(center, radius, GetColorU32(ImGuiCol_Border), 16, style.FrameBorderSize);
     }
 
     if (g.LogEnabled)
@@ -8884,18 +8895,17 @@
         // Position our combo ABOVE because there's more space to fit! (FIXME: Handle in Begin() or use a shared helper. We have similar code in Begin() for popup placement)
         popup_y1 = ImClamp(frame_bb.Min.y - popup_size.y, style.DisplaySafeAreaPadding.y, frame_bb.Min.y);
         popup_y2 = frame_bb.Min.y;
-        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Min.y + window->WindowBorderSize), ImGuiCond_Always, ImVec2(0.0f, 1.0f));
+        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Min.y + style.FrameBorderSize), ImGuiCond_Always, ImVec2(0.0f, 1.0f));
     }
     else
     {
         // Position our combo below
-        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Max.y - window->WindowBorderSize), ImGuiCond_Always, ImVec2(0.0f, 0.0f));
+        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Max.y - style.FrameBorderSize), ImGuiCond_Always, ImVec2(0.0f, 0.0f));
     }
     SetNextWindowSize(ImVec2(popup_size.x, popup_y2 - popup_y1), ImGuiCond_Appearing);
     PushStyleVar(ImGuiStyleVar_WindowPadding, style.FramePadding);
 
-    const ImGuiWindowFlags flags = ImGuiWindowFlags_ComboBox | ((window->Flags & ImGuiWindowFlags_ShowBorders) ? ImGuiWindowFlags_ShowBorders : 0);
-    if (!BeginPopupEx(id, flags))
+    if (!BeginPopupEx(id, ImGuiWindowFlags_ComboBox))
     {
         IM_ASSERT(0);   // This should never happen as we tested for IsPopupOpen() above
         return false;
@@ -9361,7 +9371,7 @@
     if (menu_is_open)
     {
         SetNextWindowPos(popup_pos, ImGuiCond_Always);
-        ImGuiWindowFlags flags = ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize | ((window->Flags & (ImGuiWindowFlags_Popup|ImGuiWindowFlags_ChildMenu)) ? ImGuiWindowFlags_ChildMenu|ImGuiWindowFlags_ChildWindow : ImGuiWindowFlags_ChildMenu);
+        ImGuiWindowFlags flags = ImGuiWindowFlags_AlwaysAutoResize | ((window->Flags & (ImGuiWindowFlags_Popup|ImGuiWindowFlags_ChildMenu)) ? ImGuiWindowFlags_ChildMenu|ImGuiWindowFlags_ChildWindow : ImGuiWindowFlags_ChildMenu);
         menu_is_open = BeginPopupEx(id, flags); // menu_is_open can be 'false' when the popup is completely clipped (e.g. zero size display)
     }
 
@@ -9506,7 +9516,7 @@
         else
             window->DrawList->AddRectFilled(bb_inner.Min, bb_inner.Max, GetColorU32(col_source), rounding, ~0);
     }
-    if (window->Flags & ImGuiWindowFlags_ShowBorders)
+    if (g.Style.FrameBorderSize > 0.0f)
         RenderFrameBorder(bb.Min, bb.Max, rounding);
     else
         window->DrawList->AddRect(bb.Min, bb.Max, GetColorU32(ImGuiCol_FrameBg), rounding); // Color button are often in need of some sort of border

diff --git a/imgui.cpp b/imgui.cpp
index 5a725c9..ca13fcd 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -214,6 +214,8 @@
  Here is a change-log of API breaking changes, if you are using one of the functions listed, expect to have to fix some code.
  Also read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2017/11/18 (1.53) - Style, Begin: removed ImGuiWindowFlags_ShowBorders window flag. Borders are now fully set up in the ImGuiStyle structure (see e.g. style.FrameBorderSize, style.WindowBorderSize). Use ImGui::ShowStyleEditor() to look them up.
+                       Please note that the style system will keep evolving (hopefully stabilizing in Q1 2018), and so custom styles will probably subtly break over time. It is recommended you use the StyleColorsClassic(), StyleColorsDark(), StyleColorsLight() functions.
  - 2017/11/18 (1.53) - Style: removed ImGuiCol_ComboBg in favor of combo boxes using ImGuiCol_PopupBg for consistency.
  - 2017/11/18 (1.53) - Style: renamed ImGuiCol_ChildWindowBg to ImGuiCol_ChildBg.
  - 2017/11/18 (1.53) - Style: renamed style.ChildWindowRounding to style.ChildRounding, ImGuiStyleVar_ChildWindowRounding to ImGuiStyleVar_ChildRounding.
@@ -704,12 +706,16 @@
     Alpha                   = 1.0f;             // Global alpha applies to everything in ImGui
     WindowPadding           = ImVec2(8,8);      // Padding within a window
     WindowRounding          = 9.0f;             // Radius of window corners rounding. Set to 0.0f to have rectangular windows
+    WindowBorderSize        = 0.0f;             // Thickness of border around windows. Generally set to 0.0f or 1.0f. Other values not well tested.
     WindowMinSize           = ImVec2(32,32);    // Minimum window size
     WindowTitleAlign        = ImVec2(0.0f,0.5f);// Alignment for title bar text
     ChildRounding           = 0.0f;             // Radius of child window corners rounding. Set to 0.0f to have rectangular child windows
+    ChildBorderSize         = 1.0f;             // Thickness of border around child windows. Generally set to 0.0f or 1.0f. Other values not well tested.
     PopupRounding           = 0.0f;             // Radius of popup window corners rounding. Set to 0.0f to have rectangular child windows
+    PopupBorderSize         = 1.0f;             // Thickness of border around popup or tooltip windows. Generally set to 0.0f or 1.0f. Other values not well tested.
     FramePadding            = ImVec2(4,3);      // Padding within a framed rectangle (used by most widgets)
     FrameRounding           = 0.0f;             // Radius of frame corners rounding. Set to 0.0f to have rectangular frames (used by most widgets).
+    FrameBorderSize         = 0.0f;             // Thickness of border around frames. Generally set to 0.0f or 1.0f. Other values not well tested.
     ItemSpacing             = ImVec2(8,4);      // Horizontal and vertical spacing between widgets/lines
     ItemInnerSpacing        = ImVec2(4,4);      // Horizontal and vertical spacing between within elements of a composed widget (e.g. a slider and its label)
     TouchExtraPadding       = ImVec2(0,0);      // Expand reactive bounding box for touch-based system where touch position is not accurate enough. Unfortunately we don't sort widgets so priority on overlap will always be given to the first widget. So don't grow this too much!
@@ -3075,10 +3081,11 @@
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
     window->DrawList->AddRectFilled(p_min, p_max, fill_col, rounding);
-    if (border && (window->Flags & ImGuiWindowFlags_ShowBorders))
+    const float border_size = g.Style.FrameBorderSize;
+    if (border && border_size > 0.0f)
     {
-        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding);
-        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding);
+        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding, ~0, border_size);
+        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding, ~0, border_size);
     }
 }
 
@@ -3086,10 +3093,11 @@
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
-    if (window->Flags & ImGuiWindowFlags_ShowBorders)
+    const float border_size = g.Style.FrameBorderSize;
+    if (border_size > 0.0f)
     {
-        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding);
-        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding);
+        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding, ~0, border_size);
+        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding, ~0, border_size);
     }
 }
 
@@ -3665,14 +3673,12 @@
 bool ImGui::BeginPopupEx(ImGuiID id, ImGuiWindowFlags extra_flags)
 {
     ImGuiContext& g = *GImGui;
-    ImGuiWindow* window = g.CurrentWindow;
     if (!IsPopupOpen(id))
     {
         ClearSetNextWindowData(); // We behave like Begin() and need to consume those values
         return false;
     }
 
-    PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
     ImGuiWindowFlags flags = extra_flags|ImGuiWindowFlags_Popup|ImGuiWindowFlags_NoTitleBar|ImGuiWindowFlags_NoResize|ImGuiWindowFlags_NoSavedSettings;
 
     char name[20];
@@ -3682,9 +3688,7 @@
         ImFormatString(name, IM_ARRAYSIZE(name), "##popup_%08x", id); // Not recycling, so we can close/open during the same frame
 
     bool is_open = Begin(name, NULL, flags);
-    if (!(window->Flags & ImGuiWindowFlags_ShowBorders))
-        g.CurrentWindow->Flags &= ~ImGuiWindowFlags_ShowBorders;
-    if (!is_open) // NB: is_open can be 'false' when the popup is completely clipped (e.g. zero size display)
+    if (!is_open) // NB: Begin can return false when the popup is completely clipped (e.g. zero size display)
         EndPopup();
 
     return is_open;
@@ -3698,7 +3702,7 @@
         ClearSetNextWindowData(); // We behave like Begin() and need to consume those values
         return false;
     }
-    return BeginPopupEx(g.CurrentWindow->GetID(str_id), ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(g.CurrentWindow->GetID(str_id), ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 bool ImGui::IsPopupOpen(ImGuiID id)
@@ -3747,8 +3751,6 @@
     IM_ASSERT(window->Flags & ImGuiWindowFlags_Popup);  // Mismatched BeginPopup()/EndPopup() calls
     IM_ASSERT(GImGui->CurrentPopupStack.Size > 0);
     End();
-    if (!(window->Flags & ImGuiWindowFlags_Modal))
-        PopStyleVar();
 }
 
 bool ImGui::OpenPopupOnItemClick(const char* str_id, int mouse_button)
@@ -3774,7 +3776,7 @@
     IM_ASSERT(id != 0);                                                  // However, you cannot pass a NULL str_id if the last item has no identifier (e.g. a Text() item)
     if (IsMouseClicked(mouse_button) && IsItemHovered(ImGuiHoveredFlags_AllowWhenBlockedByPopup))
         OpenPopupEx(id, true);
-    return BeginPopupEx(id, ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(id, ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 bool ImGui::BeginPopupContextWindow(const char* str_id, int mouse_button, bool also_over_items)
@@ -3786,7 +3788,7 @@
         if (IsWindowHovered(ImGuiHoveredFlags_AllowWhenBlockedByPopup))
             if (also_over_items || !IsAnyItemHovered())
                 OpenPopupEx(id, true);
-    return BeginPopupEx(id, ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(id, ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 bool ImGui::BeginPopupContextVoid(const char* str_id, int mouse_button)
@@ -3796,11 +3798,12 @@
     ImGuiID id = GImGui->CurrentWindow->GetID(str_id);
     if (!IsAnyWindowHovered() && IsMouseClicked(mouse_button))
         OpenPopupEx(id, true);
-    return BeginPopupEx(id, ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(id, ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 static bool BeginChildEx(const char* name, ImGuiID id, const ImVec2& size_arg, bool border, ImGuiWindowFlags extra_flags)
 {
+    ImGuiContext& g = *GImGui;
     ImGuiWindow* parent_window = ImGui::GetCurrentWindow();
     ImGuiWindowFlags flags = ImGuiWindowFlags_NoTitleBar|ImGuiWindowFlags_NoResize|ImGuiWindowFlags_NoSavedSettings|ImGuiWindowFlags_ChildWindow;
     flags |= (parent_window->Flags & ImGuiWindowFlags_NoMove);  // Inherit the NoMove flag
@@ -3812,8 +3815,10 @@
         size.x = ImMax(content_avail.x, 4.0f) - fabsf(size.x); // Arbitrary minimum zero-ish child size of 4.0f (0.0f causing too much issues)
     if (size.y <= 0.0f)
         size.y = ImMax(content_avail.y, 4.0f) - fabsf(size.y);
-    if (border)
-        flags |= ImGuiWindowFlags_ShowBorders;
+
+    const float backup_border_size = g.Style.ChildBorderSize;
+    if (!border)
+        g.Style.ChildBorderSize = 0.0f;
     flags |= extra_flags;
 
     char title[256];
@@ -3826,8 +3831,7 @@
     bool ret = ImGui::Begin(title, NULL, flags);
     ImGuiWindow* child_window = ImGui::GetCurrentWindow();
     child_window->AutoFitChildAxises = auto_fit_axises;
-    if (!(parent_window->Flags & ImGuiWindowFlags_ShowBorders))
-        child_window->Flags &= ~ImGuiWindowFlags_ShowBorders;
+    g.Style.ChildBorderSize = backup_border_size;
 
     return ret;
 }
@@ -3876,14 +3880,15 @@
     const ImGuiStyle& style = g.Style;
     PushStyleColor(ImGuiCol_ChildBg, style.Colors[ImGuiCol_FrameBg]);
     PushStyleVar(ImGuiStyleVar_ChildRounding, style.FrameRounding);
+    PushStyleVar(ImGuiStyleVar_ChildBorderSize, style.FrameBorderSize);
     PushStyleVar(ImGuiStyleVar_WindowPadding, style.FramePadding);
-    return BeginChild(id, size, (g.CurrentWindow->Flags & ImGuiWindowFlags_ShowBorders) ? true : false, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_AlwaysUseWindowPadding | extra_flags);
+    return BeginChild(id, size, true, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_AlwaysUseWindowPadding | extra_flags);
 }
 
 void ImGui::EndChildFrame()
 {
     EndChild();
-    PopStyleVar(2);
+    PopStyleVar(3);
     PopStyleColor();
 }
 
@@ -4265,13 +4270,15 @@
             }
         }
 
-        // Lock window padding so that altering the ShowBorders flag for children doesn't have side-effects.
+        // Lock window padding so that altering the border sizes for children doesn't have side-effects.
         window->WindowPadding = style.WindowPadding;
-        if ((flags & ImGuiWindowFlags_ChildWindow) && !(flags & (ImGuiWindowFlags_AlwaysUseWindowPadding | ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_ComboBox | ImGuiWindowFlags_Popup)))
+        if ((flags & ImGuiWindowFlags_ChildWindow) && !(flags & (ImGuiWindowFlags_AlwaysUseWindowPadding | ImGuiWindowFlags_ComboBox | ImGuiWindowFlags_Popup)) && style.WindowBorderSize == 0.0f)
             window->WindowPadding = ImVec2(0.0f, (flags & ImGuiWindowFlags_MenuBar) ? style.WindowPadding.y : 0.0f);
-        window->WindowBorderSize = (flags & ImGuiWindowFlags_ShowBorders) ? 1.0f : 0.0f;
         window->WindowRounding = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildRounding : ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupRounding : style.WindowRounding;
+        window->WindowBorderSize = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildBorderSize : ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupBorderSize : style.WindowBorderSize;
+        const ImVec2 window_padding = window->WindowPadding;
         const float window_rounding = window->WindowRounding;
+        const float window_border_size = window->WindowBorderSize;
 
         // Calculate auto-fit size, handle automatic resize
         const ImVec2 size_auto_fit = CalcSizeAutoFit(window);
@@ -4405,7 +4412,10 @@
         if (window->Collapsed)
         {
             // Title bar only
+            float backup_border_size = style.FrameBorderSize;
+            g.Style.FrameBorderSize = window->WindowBorderSize;
             RenderFrame(title_bar_rect.Min, title_bar_rect.Max, GetColorU32(ImGuiCol_TitleBgCollapsed), true, window_rounding);
+            g.Style.FrameBorderSize = backup_border_size;
         }
         else
         {
@@ -4459,9 +4469,9 @@
             if (flags & ImGuiWindowFlags_MenuBar)
             {
                 ImRect menu_bar_rect = window->MenuBarRect();
-                if (flags & ImGuiWindowFlags_ShowBorders)
-                    window->DrawList->AddLine(menu_bar_rect.GetBL(), menu_bar_rect.GetBR(), GetColorU32(ImGuiCol_Border));
                 window->DrawList->AddRectFilled(menu_bar_rect.GetTL(), menu_bar_rect.GetBR(), GetColorU32(ImGuiCol_MenuBarBg), (flags & ImGuiWindowFlags_NoTitleBar) ? window_rounding : 0.0f, ImGuiCorner_TopLeft|ImGuiCorner_TopRight);
+                if (style.FrameBorderSize > 0.0f)
+                    window->DrawList->AddLine(menu_bar_rect.GetBL(), menu_bar_rect.GetBR(), GetColorU32(ImGuiCol_Border), style.FrameBorderSize);
             }
 
             // Scrollbars
@@ -4475,20 +4485,17 @@
             if (!(flags & ImGuiWindowFlags_NoResize))
             {
                 const ImVec2 br = window->Rect().GetBR();
-                window->DrawList->PathLineTo(br + ImVec2(-resize_corner_size, -window->WindowBorderSize));
-                window->DrawList->PathLineTo(br + ImVec2(-window->WindowBorderSize, -resize_corner_size));
-                window->DrawList->PathArcToFast(ImVec2(br.x - window_rounding - window->WindowBorderSize, br.y - window_rounding - window->WindowBorderSize), window_rounding, 0, 3);
+                window->DrawList->PathLineTo(br + ImVec2(-resize_corner_size, -window_border_size));
+                window->DrawList->PathLineTo(br + ImVec2(-window_border_size, -resize_corner_size));
+                window->DrawList->PathArcToFast(ImVec2(br.x - window_rounding - window_border_size, br.y - window_rounding - window_border_size), window_rounding, 0, 3);
                 window->DrawList->PathFillConvex(resize_col);
             }
 
             // Borders
-            if (flags & ImGuiWindowFlags_ShowBorders)
-            {
-                window->DrawList->AddRect(window->Pos+ImVec2(1,1), window->Pos+window->Size+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), window_rounding);
-                window->DrawList->AddRect(window->Pos, window->Pos+window->Size, GetColorU32(ImGuiCol_Border), window_rounding);
-                if (!(flags & ImGuiWindowFlags_NoTitleBar))
-                    window->DrawList->AddLine(title_bar_rect.GetBL()+ImVec2(1,0), title_bar_rect.GetBR()-ImVec2(1,0), GetColorU32(ImGuiCol_Border));
-            }
+            if (window_border_size > 0.0f)
+                window->DrawList->AddRect(window->Pos, window->Pos+window->Size, GetColorU32(ImGuiCol_Border), window_rounding, ~0, window_border_size);
+            if (style.FrameBorderSize > 0 && !(flags & ImGuiWindowFlags_NoTitleBar))
+                window->DrawList->AddLine(title_bar_rect.GetBL()+ImVec2(1,-1), title_bar_rect.GetBR()+ImVec2(-1,-1), GetColorU32(ImGuiCol_Border), style.FrameBorderSize);
         }
 
         // Update ContentsRegionMax. All the variable it depends on are set above in this function.
@@ -5042,11 +5049,15 @@
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, Alpha) },                // ImGuiStyleVar_Alpha
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, WindowPadding) },        // ImGuiStyleVar_WindowPadding
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, WindowRounding) },       // ImGuiStyleVar_WindowRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, WindowBorderSize) },     // ImGuiStyleVar_WindowBorderSize
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, WindowMinSize) },        // ImGuiStyleVar_WindowMinSize
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, ChildRounding) },        // ImGuiStyleVar_ChildRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, ChildBorderSize) },      // ImGuiStyleVar_ChildBorderSize
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, PopupRounding) },        // ImGuiStyleVar_PopupRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, PopupBorderSize) },      // ImGuiStyleVar_PopupBorderSize
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, FramePadding) },         // ImGuiStyleVar_FramePadding
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, FrameRounding) },        // ImGuiStyleVar_FrameRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, FrameBorderSize) },      // ImGuiStyleVar_FrameBorderSize
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, ItemSpacing) },          // ImGuiStyleVar_ItemSpacing
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, ItemInnerSpacing) },     // ImGuiStyleVar_ItemInnerSpacing
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, IndentSpacing) },        // ImGuiStyleVar_IndentSpacing
@@ -7619,7 +7630,7 @@
     // Render
     fraction = ImSaturate(fraction);
     RenderFrame(bb.Min, bb.Max, GetColorU32(ImGuiCol_FrameBg), true, style.FrameRounding);
-    bb.Expand(ImVec2(-window->WindowBorderSize, -window->WindowBorderSize));
+    bb.Expand(ImVec2(-style.FrameBorderSize, -style.FrameBorderSize));
     const ImVec2 fill_br = ImVec2(ImLerp(bb.Min.x, bb.Max.x, fraction), bb.Max.y);
     RenderRectFilledRangeH(window->DrawList, bb, GetColorU32(ImGuiCol_PlotHistogram), 0.0f, fraction, style.FrameRounding);
 
@@ -7742,10 +7753,10 @@
         window->DrawList->AddCircleFilled(center, radius-pad, GetColorU32(ImGuiCol_CheckMark), 16);
     }
 
-    if (window->Flags & ImGuiWindowFlags_ShowBorders)
+    if (style.FrameBorderSize > 0.0f)
     {
-        window->DrawList->AddCircle(center+ImVec2(1,1), radius, GetColorU32(ImGuiCol_BorderShadow), 16);
-        window->DrawList->AddCircle(center, radius, GetColorU32(ImGuiCol_Border), 16);
+        window->DrawList->AddCircle(center+ImVec2(1,1), radius, GetColorU32(ImGuiCol_BorderShadow), 16, style.FrameBorderSize);
+        window->DrawList->AddCircle(center, radius, GetColorU32(ImGuiCol_Border), 16, style.FrameBorderSize);
     }
 
     if (g.LogEnabled)
@@ -8884,18 +8895,17 @@
         // Position our combo ABOVE because there's more space to fit! (FIXME: Handle in Begin() or use a shared helper. We have similar code in Begin() for popup placement)
         popup_y1 = ImClamp(frame_bb.Min.y - popup_size.y, style.DisplaySafeAreaPadding.y, frame_bb.Min.y);
         popup_y2 = frame_bb.Min.y;
-        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Min.y + window->WindowBorderSize), ImGuiCond_Always, ImVec2(0.0f, 1.0f));
+        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Min.y + style.FrameBorderSize), ImGuiCond_Always, ImVec2(0.0f, 1.0f));
     }
     else
     {
         // Position our combo below
-        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Max.y - window->WindowBorderSize), ImGuiCond_Always, ImVec2(0.0f, 0.0f));
+        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Max.y - style.FrameBorderSize), ImGuiCond_Always, ImVec2(0.0f, 0.0f));
     }
     SetNextWindowSize(ImVec2(popup_size.x, popup_y2 - popup_y1), ImGuiCond_Appearing);
     PushStyleVar(ImGuiStyleVar_WindowPadding, style.FramePadding);
 
-    const ImGuiWindowFlags flags = ImGuiWindowFlags_ComboBox | ((window->Flags & ImGuiWindowFlags_ShowBorders) ? ImGuiWindowFlags_ShowBorders : 0);
-    if (!BeginPopupEx(id, flags))
+    if (!BeginPopupEx(id, ImGuiWindowFlags_ComboBox))
     {
         IM_ASSERT(0);   // This should never happen as we tested for IsPopupOpen() above
         return false;
@@ -9361,7 +9371,7 @@
     if (menu_is_open)
     {
         SetNextWindowPos(popup_pos, ImGuiCond_Always);
-        ImGuiWindowFlags flags = ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize | ((window->Flags & (ImGuiWindowFlags_Popup|ImGuiWindowFlags_ChildMenu)) ? ImGuiWindowFlags_ChildMenu|ImGuiWindowFlags_ChildWindow : ImGuiWindowFlags_ChildMenu);
+        ImGuiWindowFlags flags = ImGuiWindowFlags_AlwaysAutoResize | ((window->Flags & (ImGuiWindowFlags_Popup|ImGuiWindowFlags_ChildMenu)) ? ImGuiWindowFlags_ChildMenu|ImGuiWindowFlags_ChildWindow : ImGuiWindowFlags_ChildMenu);
         menu_is_open = BeginPopupEx(id, flags); // menu_is_open can be 'false' when the popup is completely clipped (e.g. zero size display)
     }
 
@@ -9506,7 +9516,7 @@
         else
             window->DrawList->AddRectFilled(bb_inner.Min, bb_inner.Max, GetColorU32(col_source), rounding, ~0);
     }
-    if (window->Flags & ImGuiWindowFlags_ShowBorders)
+    if (g.Style.FrameBorderSize > 0.0f)
         RenderFrameBorder(bb.Min, bb.Max, rounding);
     else
         window->DrawList->AddRect(bb.Min, bb.Max, GetColorU32(ImGuiCol_FrameBg), rounding); // Color button are often in need of some sort of border
diff --git a/imgui.h b/imgui.h
index 5515940..98e016b 100644
--- a/imgui.h
+++ b/imgui.h
@@ -502,7 +502,7 @@
     ImGuiWindowFlags_NoScrollWithMouse      = 1 << 4,   // Disable user vertically scrolling with mouse wheel
     ImGuiWindowFlags_NoCollapse             = 1 << 5,   // Disable user collapsing window by double-clicking on it
     ImGuiWindowFlags_AlwaysAutoResize       = 1 << 6,   // Resize every window to its content every frame
-    ImGuiWindowFlags_ShowBorders            = 1 << 7,   // Show borders around windows and items
+    //ImGuiWindowFlags_ShowBorders          = 1 << 7,   // Show borders around windows and items (OBSOLETE! Use e.g. style.FrameBorderSize=1.0f to enable borders).
     ImGuiWindowFlags_NoSavedSettings        = 1 << 8,   // Never load/save settings in .ini file
     ImGuiWindowFlags_NoInputs               = 1 << 9,   // Disable catching mouse or keyboard inputs, hovering test with pass through.
     ImGuiWindowFlags_MenuBar                = 1 << 10,  // Has a menu-bar
@@ -672,11 +672,15 @@
     ImGuiStyleVar_Alpha,               // float     Alpha
     ImGuiStyleVar_WindowPadding,       // ImVec2    WindowPadding
     ImGuiStyleVar_WindowRounding,      // float     WindowRounding
+    ImGuiStyleVar_WindowBorderSize,    // float     WindowBorderSize
     ImGuiStyleVar_WindowMinSize,       // ImVec2    WindowMinSize
     ImGuiStyleVar_ChildRounding,       // float     ChildRounding
+    ImGuiStyleVar_ChildBorderSize,     // float     ChildBorderSize
     ImGuiStyleVar_PopupRounding,       // float     PopupRounding
+    ImGuiStyleVar_PopupBorderSize,     // float     PopupBorderSize
     ImGuiStyleVar_FramePadding,        // ImVec2    FramePadding
     ImGuiStyleVar_FrameRounding,       // float     FrameRounding
+    ImGuiStyleVar_FrameBorderSize,     // float     FrameBorderSize
     ImGuiStyleVar_ItemSpacing,         // ImVec2    ItemSpacing
     ImGuiStyleVar_ItemInnerSpacing,    // ImVec2    ItemInnerSpacing
     ImGuiStyleVar_IndentSpacing,       // float     IndentSpacing
@@ -754,12 +758,16 @@
     float       Alpha;                      // Global alpha applies to everything in ImGui
     ImVec2      WindowPadding;              // Padding within a window
     float       WindowRounding;             // Radius of window corners rounding. Set to 0.0f to have rectangular windows
+    float       WindowBorderSize;           // Thickness of border around windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly)
     ImVec2      WindowMinSize;              // Minimum window size
     ImVec2      WindowTitleAlign;           // Alignment for title bar text. Defaults to (0.0f,0.5f) for left-aligned,vertically centered.
     float       ChildRounding;              // Radius of child window corners rounding. Set to 0.0f to have rectangular windows.
+    float       ChildBorderSize;            // Thickness of border around child windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly)
     float       PopupRounding;              // Radius of popup window corners rounding.
+    float       PopupBorderSize;            // Thickness of border around popup windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly)
     ImVec2      FramePadding;               // Padding within a framed rectangle (used by most widgets)
     float       FrameRounding;              // Radius of frame corners rounding. Set to 0.0f to have rectangular frame (used by most widgets).
+    float       FrameBorderSize;            // Thickness of border around frames. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly)
     ImVec2      ItemSpacing;                // Horizontal and vertical spacing between widgets/lines
     ImVec2      ItemInnerSpacing;           // Horizontal and vertical spacing between within elements of a composed widget (e.g. a slider and its label)
     ImVec2      TouchExtraPadding;          // Expand reactive bounding box for touch-based system where touch position is not accurate enough. Unfortunately we don't sort widgets so priority on overlap will always be given to the first widget. So don't grow this too much!

diff --git a/imgui.cpp b/imgui.cpp
index 5a725c9..ca13fcd 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -214,6 +214,8 @@
  Here is a change-log of API breaking changes, if you are using one of the functions listed, expect to have to fix some code.
  Also read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2017/11/18 (1.53) - Style, Begin: removed ImGuiWindowFlags_ShowBorders window flag. Borders are now fully set up in the ImGuiStyle structure (see e.g. style.FrameBorderSize, style.WindowBorderSize). Use ImGui::ShowStyleEditor() to look them up.
+                       Please note that the style system will keep evolving (hopefully stabilizing in Q1 2018), and so custom styles will probably subtly break over time. It is recommended you use the StyleColorsClassic(), StyleColorsDark(), StyleColorsLight() functions.
  - 2017/11/18 (1.53) - Style: removed ImGuiCol_ComboBg in favor of combo boxes using ImGuiCol_PopupBg for consistency.
  - 2017/11/18 (1.53) - Style: renamed ImGuiCol_ChildWindowBg to ImGuiCol_ChildBg.
  - 2017/11/18 (1.53) - Style: renamed style.ChildWindowRounding to style.ChildRounding, ImGuiStyleVar_ChildWindowRounding to ImGuiStyleVar_ChildRounding.
@@ -704,12 +706,16 @@
     Alpha                   = 1.0f;             // Global alpha applies to everything in ImGui
     WindowPadding           = ImVec2(8,8);      // Padding within a window
     WindowRounding          = 9.0f;             // Radius of window corners rounding. Set to 0.0f to have rectangular windows
+    WindowBorderSize        = 0.0f;             // Thickness of border around windows. Generally set to 0.0f or 1.0f. Other values not well tested.
     WindowMinSize           = ImVec2(32,32);    // Minimum window size
     WindowTitleAlign        = ImVec2(0.0f,0.5f);// Alignment for title bar text
     ChildRounding           = 0.0f;             // Radius of child window corners rounding. Set to 0.0f to have rectangular child windows
+    ChildBorderSize         = 1.0f;             // Thickness of border around child windows. Generally set to 0.0f or 1.0f. Other values not well tested.
     PopupRounding           = 0.0f;             // Radius of popup window corners rounding. Set to 0.0f to have rectangular child windows
+    PopupBorderSize         = 1.0f;             // Thickness of border around popup or tooltip windows. Generally set to 0.0f or 1.0f. Other values not well tested.
     FramePadding            = ImVec2(4,3);      // Padding within a framed rectangle (used by most widgets)
     FrameRounding           = 0.0f;             // Radius of frame corners rounding. Set to 0.0f to have rectangular frames (used by most widgets).
+    FrameBorderSize         = 0.0f;             // Thickness of border around frames. Generally set to 0.0f or 1.0f. Other values not well tested.
     ItemSpacing             = ImVec2(8,4);      // Horizontal and vertical spacing between widgets/lines
     ItemInnerSpacing        = ImVec2(4,4);      // Horizontal and vertical spacing between within elements of a composed widget (e.g. a slider and its label)
     TouchExtraPadding       = ImVec2(0,0);      // Expand reactive bounding box for touch-based system where touch position is not accurate enough. Unfortunately we don't sort widgets so priority on overlap will always be given to the first widget. So don't grow this too much!
@@ -3075,10 +3081,11 @@
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
     window->DrawList->AddRectFilled(p_min, p_max, fill_col, rounding);
-    if (border && (window->Flags & ImGuiWindowFlags_ShowBorders))
+    const float border_size = g.Style.FrameBorderSize;
+    if (border && border_size > 0.0f)
     {
-        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding);
-        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding);
+        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding, ~0, border_size);
+        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding, ~0, border_size);
     }
 }
 
@@ -3086,10 +3093,11 @@
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
-    if (window->Flags & ImGuiWindowFlags_ShowBorders)
+    const float border_size = g.Style.FrameBorderSize;
+    if (border_size > 0.0f)
     {
-        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding);
-        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding);
+        window->DrawList->AddRect(p_min+ImVec2(1,1), p_max+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), rounding, ~0, border_size);
+        window->DrawList->AddRect(p_min, p_max, GetColorU32(ImGuiCol_Border), rounding, ~0, border_size);
     }
 }
 
@@ -3665,14 +3673,12 @@
 bool ImGui::BeginPopupEx(ImGuiID id, ImGuiWindowFlags extra_flags)
 {
     ImGuiContext& g = *GImGui;
-    ImGuiWindow* window = g.CurrentWindow;
     if (!IsPopupOpen(id))
     {
         ClearSetNextWindowData(); // We behave like Begin() and need to consume those values
         return false;
     }
 
-    PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
     ImGuiWindowFlags flags = extra_flags|ImGuiWindowFlags_Popup|ImGuiWindowFlags_NoTitleBar|ImGuiWindowFlags_NoResize|ImGuiWindowFlags_NoSavedSettings;
 
     char name[20];
@@ -3682,9 +3688,7 @@
         ImFormatString(name, IM_ARRAYSIZE(name), "##popup_%08x", id); // Not recycling, so we can close/open during the same frame
 
     bool is_open = Begin(name, NULL, flags);
-    if (!(window->Flags & ImGuiWindowFlags_ShowBorders))
-        g.CurrentWindow->Flags &= ~ImGuiWindowFlags_ShowBorders;
-    if (!is_open) // NB: is_open can be 'false' when the popup is completely clipped (e.g. zero size display)
+    if (!is_open) // NB: Begin can return false when the popup is completely clipped (e.g. zero size display)
         EndPopup();
 
     return is_open;
@@ -3698,7 +3702,7 @@
         ClearSetNextWindowData(); // We behave like Begin() and need to consume those values
         return false;
     }
-    return BeginPopupEx(g.CurrentWindow->GetID(str_id), ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(g.CurrentWindow->GetID(str_id), ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 bool ImGui::IsPopupOpen(ImGuiID id)
@@ -3747,8 +3751,6 @@
     IM_ASSERT(window->Flags & ImGuiWindowFlags_Popup);  // Mismatched BeginPopup()/EndPopup() calls
     IM_ASSERT(GImGui->CurrentPopupStack.Size > 0);
     End();
-    if (!(window->Flags & ImGuiWindowFlags_Modal))
-        PopStyleVar();
 }
 
 bool ImGui::OpenPopupOnItemClick(const char* str_id, int mouse_button)
@@ -3774,7 +3776,7 @@
     IM_ASSERT(id != 0);                                                  // However, you cannot pass a NULL str_id if the last item has no identifier (e.g. a Text() item)
     if (IsMouseClicked(mouse_button) && IsItemHovered(ImGuiHoveredFlags_AllowWhenBlockedByPopup))
         OpenPopupEx(id, true);
-    return BeginPopupEx(id, ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(id, ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 bool ImGui::BeginPopupContextWindow(const char* str_id, int mouse_button, bool also_over_items)
@@ -3786,7 +3788,7 @@
         if (IsWindowHovered(ImGuiHoveredFlags_AllowWhenBlockedByPopup))
             if (also_over_items || !IsAnyItemHovered())
                 OpenPopupEx(id, true);
-    return BeginPopupEx(id, ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(id, ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 bool ImGui::BeginPopupContextVoid(const char* str_id, int mouse_button)
@@ -3796,11 +3798,12 @@
     ImGuiID id = GImGui->CurrentWindow->GetID(str_id);
     if (!IsAnyWindowHovered() && IsMouseClicked(mouse_button))
         OpenPopupEx(id, true);
-    return BeginPopupEx(id, ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize);
+    return BeginPopupEx(id, ImGuiWindowFlags_AlwaysAutoResize);
 }
 
 static bool BeginChildEx(const char* name, ImGuiID id, const ImVec2& size_arg, bool border, ImGuiWindowFlags extra_flags)
 {
+    ImGuiContext& g = *GImGui;
     ImGuiWindow* parent_window = ImGui::GetCurrentWindow();
     ImGuiWindowFlags flags = ImGuiWindowFlags_NoTitleBar|ImGuiWindowFlags_NoResize|ImGuiWindowFlags_NoSavedSettings|ImGuiWindowFlags_ChildWindow;
     flags |= (parent_window->Flags & ImGuiWindowFlags_NoMove);  // Inherit the NoMove flag
@@ -3812,8 +3815,10 @@
         size.x = ImMax(content_avail.x, 4.0f) - fabsf(size.x); // Arbitrary minimum zero-ish child size of 4.0f (0.0f causing too much issues)
     if (size.y <= 0.0f)
         size.y = ImMax(content_avail.y, 4.0f) - fabsf(size.y);
-    if (border)
-        flags |= ImGuiWindowFlags_ShowBorders;
+
+    const float backup_border_size = g.Style.ChildBorderSize;
+    if (!border)
+        g.Style.ChildBorderSize = 0.0f;
     flags |= extra_flags;
 
     char title[256];
@@ -3826,8 +3831,7 @@
     bool ret = ImGui::Begin(title, NULL, flags);
     ImGuiWindow* child_window = ImGui::GetCurrentWindow();
     child_window->AutoFitChildAxises = auto_fit_axises;
-    if (!(parent_window->Flags & ImGuiWindowFlags_ShowBorders))
-        child_window->Flags &= ~ImGuiWindowFlags_ShowBorders;
+    g.Style.ChildBorderSize = backup_border_size;
 
     return ret;
 }
@@ -3876,14 +3880,15 @@
     const ImGuiStyle& style = g.Style;
     PushStyleColor(ImGuiCol_ChildBg, style.Colors[ImGuiCol_FrameBg]);
     PushStyleVar(ImGuiStyleVar_ChildRounding, style.FrameRounding);
+    PushStyleVar(ImGuiStyleVar_ChildBorderSize, style.FrameBorderSize);
     PushStyleVar(ImGuiStyleVar_WindowPadding, style.FramePadding);
-    return BeginChild(id, size, (g.CurrentWindow->Flags & ImGuiWindowFlags_ShowBorders) ? true : false, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_AlwaysUseWindowPadding | extra_flags);
+    return BeginChild(id, size, true, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_AlwaysUseWindowPadding | extra_flags);
 }
 
 void ImGui::EndChildFrame()
 {
     EndChild();
-    PopStyleVar(2);
+    PopStyleVar(3);
     PopStyleColor();
 }
 
@@ -4265,13 +4270,15 @@
             }
         }
 
-        // Lock window padding so that altering the ShowBorders flag for children doesn't have side-effects.
+        // Lock window padding so that altering the border sizes for children doesn't have side-effects.
         window->WindowPadding = style.WindowPadding;
-        if ((flags & ImGuiWindowFlags_ChildWindow) && !(flags & (ImGuiWindowFlags_AlwaysUseWindowPadding | ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_ComboBox | ImGuiWindowFlags_Popup)))
+        if ((flags & ImGuiWindowFlags_ChildWindow) && !(flags & (ImGuiWindowFlags_AlwaysUseWindowPadding | ImGuiWindowFlags_ComboBox | ImGuiWindowFlags_Popup)) && style.WindowBorderSize == 0.0f)
             window->WindowPadding = ImVec2(0.0f, (flags & ImGuiWindowFlags_MenuBar) ? style.WindowPadding.y : 0.0f);
-        window->WindowBorderSize = (flags & ImGuiWindowFlags_ShowBorders) ? 1.0f : 0.0f;
         window->WindowRounding = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildRounding : ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupRounding : style.WindowRounding;
+        window->WindowBorderSize = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildBorderSize : ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupBorderSize : style.WindowBorderSize;
+        const ImVec2 window_padding = window->WindowPadding;
         const float window_rounding = window->WindowRounding;
+        const float window_border_size = window->WindowBorderSize;
 
         // Calculate auto-fit size, handle automatic resize
         const ImVec2 size_auto_fit = CalcSizeAutoFit(window);
@@ -4405,7 +4412,10 @@
         if (window->Collapsed)
         {
             // Title bar only
+            float backup_border_size = style.FrameBorderSize;
+            g.Style.FrameBorderSize = window->WindowBorderSize;
             RenderFrame(title_bar_rect.Min, title_bar_rect.Max, GetColorU32(ImGuiCol_TitleBgCollapsed), true, window_rounding);
+            g.Style.FrameBorderSize = backup_border_size;
         }
         else
         {
@@ -4459,9 +4469,9 @@
             if (flags & ImGuiWindowFlags_MenuBar)
             {
                 ImRect menu_bar_rect = window->MenuBarRect();
-                if (flags & ImGuiWindowFlags_ShowBorders)
-                    window->DrawList->AddLine(menu_bar_rect.GetBL(), menu_bar_rect.GetBR(), GetColorU32(ImGuiCol_Border));
                 window->DrawList->AddRectFilled(menu_bar_rect.GetTL(), menu_bar_rect.GetBR(), GetColorU32(ImGuiCol_MenuBarBg), (flags & ImGuiWindowFlags_NoTitleBar) ? window_rounding : 0.0f, ImGuiCorner_TopLeft|ImGuiCorner_TopRight);
+                if (style.FrameBorderSize > 0.0f)
+                    window->DrawList->AddLine(menu_bar_rect.GetBL(), menu_bar_rect.GetBR(), GetColorU32(ImGuiCol_Border), style.FrameBorderSize);
             }
 
             // Scrollbars
@@ -4475,20 +4485,17 @@
             if (!(flags & ImGuiWindowFlags_NoResize))
             {
                 const ImVec2 br = window->Rect().GetBR();
-                window->DrawList->PathLineTo(br + ImVec2(-resize_corner_size, -window->WindowBorderSize));
-                window->DrawList->PathLineTo(br + ImVec2(-window->WindowBorderSize, -resize_corner_size));
-                window->DrawList->PathArcToFast(ImVec2(br.x - window_rounding - window->WindowBorderSize, br.y - window_rounding - window->WindowBorderSize), window_rounding, 0, 3);
+                window->DrawList->PathLineTo(br + ImVec2(-resize_corner_size, -window_border_size));
+                window->DrawList->PathLineTo(br + ImVec2(-window_border_size, -resize_corner_size));
+                window->DrawList->PathArcToFast(ImVec2(br.x - window_rounding - window_border_size, br.y - window_rounding - window_border_size), window_rounding, 0, 3);
                 window->DrawList->PathFillConvex(resize_col);
             }
 
             // Borders
-            if (flags & ImGuiWindowFlags_ShowBorders)
-            {
-                window->DrawList->AddRect(window->Pos+ImVec2(1,1), window->Pos+window->Size+ImVec2(1,1), GetColorU32(ImGuiCol_BorderShadow), window_rounding);
-                window->DrawList->AddRect(window->Pos, window->Pos+window->Size, GetColorU32(ImGuiCol_Border), window_rounding);
-                if (!(flags & ImGuiWindowFlags_NoTitleBar))
-                    window->DrawList->AddLine(title_bar_rect.GetBL()+ImVec2(1,0), title_bar_rect.GetBR()-ImVec2(1,0), GetColorU32(ImGuiCol_Border));
-            }
+            if (window_border_size > 0.0f)
+                window->DrawList->AddRect(window->Pos, window->Pos+window->Size, GetColorU32(ImGuiCol_Border), window_rounding, ~0, window_border_size);
+            if (style.FrameBorderSize > 0 && !(flags & ImGuiWindowFlags_NoTitleBar))
+                window->DrawList->AddLine(title_bar_rect.GetBL()+ImVec2(1,-1), title_bar_rect.GetBR()+ImVec2(-1,-1), GetColorU32(ImGuiCol_Border), style.FrameBorderSize);
         }
 
         // Update ContentsRegionMax. All the variable it depends on are set above in this function.
@@ -5042,11 +5049,15 @@
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, Alpha) },                // ImGuiStyleVar_Alpha
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, WindowPadding) },        // ImGuiStyleVar_WindowPadding
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, WindowRounding) },       // ImGuiStyleVar_WindowRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, WindowBorderSize) },     // ImGuiStyleVar_WindowBorderSize
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, WindowMinSize) },        // ImGuiStyleVar_WindowMinSize
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, ChildRounding) },        // ImGuiStyleVar_ChildRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, ChildBorderSize) },      // ImGuiStyleVar_ChildBorderSize
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, PopupRounding) },        // ImGuiStyleVar_PopupRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, PopupBorderSize) },      // ImGuiStyleVar_PopupBorderSize
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, FramePadding) },         // ImGuiStyleVar_FramePadding
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, FrameRounding) },        // ImGuiStyleVar_FrameRounding
+    { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, FrameBorderSize) },      // ImGuiStyleVar_FrameBorderSize
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, ItemSpacing) },          // ImGuiStyleVar_ItemSpacing
     { ImGuiDataType_Float2, (ImU32)IM_OFFSETOF(ImGuiStyle, ItemInnerSpacing) },     // ImGuiStyleVar_ItemInnerSpacing
     { ImGuiDataType_Float,  (ImU32)IM_OFFSETOF(ImGuiStyle, IndentSpacing) },        // ImGuiStyleVar_IndentSpacing
@@ -7619,7 +7630,7 @@
     // Render
     fraction = ImSaturate(fraction);
     RenderFrame(bb.Min, bb.Max, GetColorU32(ImGuiCol_FrameBg), true, style.FrameRounding);
-    bb.Expand(ImVec2(-window->WindowBorderSize, -window->WindowBorderSize));
+    bb.Expand(ImVec2(-style.FrameBorderSize, -style.FrameBorderSize));
     const ImVec2 fill_br = ImVec2(ImLerp(bb.Min.x, bb.Max.x, fraction), bb.Max.y);
     RenderRectFilledRangeH(window->DrawList, bb, GetColorU32(ImGuiCol_PlotHistogram), 0.0f, fraction, style.FrameRounding);
 
@@ -7742,10 +7753,10 @@
         window->DrawList->AddCircleFilled(center, radius-pad, GetColorU32(ImGuiCol_CheckMark), 16);
     }
 
-    if (window->Flags & ImGuiWindowFlags_ShowBorders)
+    if (style.FrameBorderSize > 0.0f)
     {
-        window->DrawList->AddCircle(center+ImVec2(1,1), radius, GetColorU32(ImGuiCol_BorderShadow), 16);
-        window->DrawList->AddCircle(center, radius, GetColorU32(ImGuiCol_Border), 16);
+        window->DrawList->AddCircle(center+ImVec2(1,1), radius, GetColorU32(ImGuiCol_BorderShadow), 16, style.FrameBorderSize);
+        window->DrawList->AddCircle(center, radius, GetColorU32(ImGuiCol_Border), 16, style.FrameBorderSize);
     }
 
     if (g.LogEnabled)
@@ -8884,18 +8895,17 @@
         // Position our combo ABOVE because there's more space to fit! (FIXME: Handle in Begin() or use a shared helper. We have similar code in Begin() for popup placement)
         popup_y1 = ImClamp(frame_bb.Min.y - popup_size.y, style.DisplaySafeAreaPadding.y, frame_bb.Min.y);
         popup_y2 = frame_bb.Min.y;
-        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Min.y + window->WindowBorderSize), ImGuiCond_Always, ImVec2(0.0f, 1.0f));
+        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Min.y + style.FrameBorderSize), ImGuiCond_Always, ImVec2(0.0f, 1.0f));
     }
     else
     {
         // Position our combo below
-        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Max.y - window->WindowBorderSize), ImGuiCond_Always, ImVec2(0.0f, 0.0f));
+        SetNextWindowPos(ImVec2(frame_bb.Min.x, frame_bb.Max.y - style.FrameBorderSize), ImGuiCond_Always, ImVec2(0.0f, 0.0f));
     }
     SetNextWindowSize(ImVec2(popup_size.x, popup_y2 - popup_y1), ImGuiCond_Appearing);
     PushStyleVar(ImGuiStyleVar_WindowPadding, style.FramePadding);
 
-    const ImGuiWindowFlags flags = ImGuiWindowFlags_ComboBox | ((window->Flags & ImGuiWindowFlags_ShowBorders) ? ImGuiWindowFlags_ShowBorders : 0);
-    if (!BeginPopupEx(id, flags))
+    if (!BeginPopupEx(id, ImGuiWindowFlags_ComboBox))
     {
         IM_ASSERT(0);   // This should never happen as we tested for IsPopupOpen() above
         return false;
@@ -9361,7 +9371,7 @@
     if (menu_is_open)
     {
         SetNextWindowPos(popup_pos, ImGuiCond_Always);
-        ImGuiWindowFlags flags = ImGuiWindowFlags_ShowBorders | ImGuiWindowFlags_AlwaysAutoResize | ((window->Flags & (ImGuiWindowFlags_Popup|ImGuiWindowFlags_ChildMenu)) ? ImGuiWindowFlags_ChildMenu|ImGuiWindowFlags_ChildWindow : ImGuiWindowFlags_ChildMenu);
+        ImGuiWindowFlags flags = ImGuiWindowFlags_AlwaysAutoResize | ((window->Flags & (ImGuiWindowFlags_Popup|ImGuiWindowFlags_ChildMenu)) ? ImGuiWindowFlags_ChildMenu|ImGuiWindowFlags_ChildWindow : ImGuiWindowFlags_ChildMenu);
         menu_is_open = BeginPopupEx(id, flags); // menu_is_open can be 'false' when the popup is completely clipped (e.g. zero size display)
     }
 
@@ -9506,7 +9516,7 @@
         else
             window->DrawList->AddRectFilled(bb_inner.Min, bb_inner.Max, GetColorU32(col_source), rounding, ~0);
     }
-    if (window->Flags & ImGuiWindowFlags_ShowBorders)
+    if (g.Style.FrameBorderSize > 0.0f)
         RenderFrameBorder(bb.Min, bb.Max, rounding);
     else
         window->DrawList->AddRect(bb.Min, bb.Max, GetColorU32(ImGuiCol_FrameBg), rounding); // Color button are often in need of some sort of border
diff --git a/imgui.h b/imgui.h
index 5515940..98e016b 100644
--- a/imgui.h
+++ b/imgui.h
@@ -502,7 +502,7 @@
     ImGuiWindowFlags_NoScrollWithMouse      = 1 << 4,   // Disable user vertically scrolling with mouse wheel
     ImGuiWindowFlags_NoCollapse             = 1 << 5,   // Disable user collapsing window by double-clicking on it
     ImGuiWindowFlags_AlwaysAutoResize       = 1 << 6,   // Resize every window to its content every frame
-    ImGuiWindowFlags_ShowBorders            = 1 << 7,   // Show borders around windows and items
+    //ImGuiWindowFlags_ShowBorders          = 1 << 7,   // Show borders around windows and items (OBSOLETE! Use e.g. style.FrameBorderSize=1.0f to enable borders).
     ImGuiWindowFlags_NoSavedSettings        = 1 << 8,   // Never load/save settings in .ini file
     ImGuiWindowFlags_NoInputs               = 1 << 9,   // Disable catching mouse or keyboard inputs, hovering test with pass through.
     ImGuiWindowFlags_MenuBar                = 1 << 10,  // Has a menu-bar
@@ -672,11 +672,15 @@
     ImGuiStyleVar_Alpha,               // float     Alpha
     ImGuiStyleVar_WindowPadding,       // ImVec2    WindowPadding
     ImGuiStyleVar_WindowRounding,      // float     WindowRounding
+    ImGuiStyleVar_WindowBorderSize,    // float     WindowBorderSize
     ImGuiStyleVar_WindowMinSize,       // ImVec2    WindowMinSize
     ImGuiStyleVar_ChildRounding,       // float     ChildRounding
+    ImGuiStyleVar_ChildBorderSize,     // float     ChildBorderSize
     ImGuiStyleVar_PopupRounding,       // float     PopupRounding
+    ImGuiStyleVar_PopupBorderSize,     // float     PopupBorderSize
     ImGuiStyleVar_FramePadding,        // ImVec2    FramePadding
     ImGuiStyleVar_FrameRounding,       // float     FrameRounding
+    ImGuiStyleVar_FrameBorderSize,     // float     FrameBorderSize
     ImGuiStyleVar_ItemSpacing,         // ImVec2    ItemSpacing
     ImGuiStyleVar_ItemInnerSpacing,    // ImVec2    ItemInnerSpacing
     ImGuiStyleVar_IndentSpacing,       // float     IndentSpacing
@@ -754,12 +758,16 @@
     float       Alpha;                      // Global alpha applies to everything in ImGui
     ImVec2      WindowPadding;              // Padding within a window
     float       WindowRounding;             // Radius of window corners rounding. Set to 0.0f to have rectangular windows
+    float       WindowBorderSize;           // Thickness of border around windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly)
     ImVec2      WindowMinSize;              // Minimum window size
     ImVec2      WindowTitleAlign;           // Alignment for title bar text. Defaults to (0.0f,0.5f) for left-aligned,vertically centered.
     float       ChildRounding;              // Radius of child window corners rounding. Set to 0.0f to have rectangular windows.
+    float       ChildBorderSize;            // Thickness of border around child windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly)
     float       PopupRounding;              // Radius of popup window corners rounding.
+    float       PopupBorderSize;            // Thickness of border around popup windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly)
     ImVec2      FramePadding;               // Padding within a framed rectangle (used by most widgets)
     float       FrameRounding;              // Radius of frame corners rounding. Set to 0.0f to have rectangular frame (used by most widgets).
+    float       FrameBorderSize;            // Thickness of border around frames. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly)
     ImVec2      ItemSpacing;                // Horizontal and vertical spacing between widgets/lines
     ImVec2      ItemInnerSpacing;           // Horizontal and vertical spacing between within elements of a composed widget (e.g. a slider and its label)
     ImVec2      TouchExtraPadding;          // Expand reactive bounding box for touch-based system where touch position is not accurate enough. Unfortunately we don't sort widgets so priority on overlap will always be given to the first widget. So don't grow this too much!
diff --git a/imgui_demo.cpp b/imgui_demo.cpp
index d6475d0..7ee7de8 100644
--- a/imgui_demo.cpp
+++ b/imgui_demo.cpp
@@ -165,22 +165,20 @@
     }
 
     static bool no_titlebar = false;
-    static bool no_border = true;
-    static bool no_resize = false;
-    static bool no_move = false;
     static bool no_scrollbar = false;
-    static bool no_collapse = false;
     static bool no_menu = false;
+    static bool no_move = false;
+    static bool no_resize = false;
+    static bool no_collapse = false;
 
     // Demonstrate the various window flags. Typically you would just use the default.
     ImGuiWindowFlags window_flags = 0;
     if (no_titlebar)  window_flags |= ImGuiWindowFlags_NoTitleBar;
-    if (!no_border)   window_flags |= ImGuiWindowFlags_ShowBorders;
-    if (no_resize)    window_flags |= ImGuiWindowFlags_NoResize;
-    if (no_move)      window_flags |= ImGuiWindowFlags_NoMove;
     if (no_scrollbar) window_flags |= ImGuiWindowFlags_NoScrollbar;
-    if (no_collapse)  window_flags |= ImGuiWindowFlags_NoCollapse;
     if (!no_menu)     window_flags |= ImGuiWindowFlags_MenuBar;
+    if (no_move)      window_flags |= ImGuiWindowFlags_NoMove;
+    if (no_resize)    window_flags |= ImGuiWindowFlags_NoResize;
+    if (no_collapse)  window_flags |= ImGuiWindowFlags_NoCollapse;
     ImGui::SetNextWindowSize(ImVec2(550,680), ImGuiCond_FirstUseEver);
     if (!ImGui::Begin("ImGui Demo", p_open, window_flags))
     {
@@ -238,12 +236,11 @@
     if (ImGui::CollapsingHeader("Window options"))
     {
         ImGui::Checkbox("No titlebar", &no_titlebar); ImGui::SameLine(150);
-        ImGui::Checkbox("No border", &no_border); ImGui::SameLine(300);
-        ImGui::Checkbox("No resize", &no_resize);
-        ImGui::Checkbox("No move", &no_move); ImGui::SameLine(150);
         ImGui::Checkbox("No scrollbar", &no_scrollbar); ImGui::SameLine(300);
-        ImGui::Checkbox("No collapse", &no_collapse);
         ImGui::Checkbox("No menu", &no_menu);
+        ImGui::Checkbox("No move", &no_move); ImGui::SameLine(150);
+        ImGui::Checkbox("No resize", &no_resize); ImGui::SameLine(300);
+        ImGui::Checkbox("No collapse", &no_collapse);
 
         if (ImGui::TreeNode("Style"))
         {
@@ -685,7 +682,6 @@
             ImGui::TreePop();
         }
 
-
         if (ImGui::TreeNode("Plots widgets"))
         {
             static bool animate = true;
@@ -1878,6 +1874,17 @@
         ref_saved_style = style;
     }
 
+    // Simplified Settings
+    if (ImGui::SliderFloat("FrameRounding", &style.FrameRounding, 0.0f, 12.0f, "%.0f")) 
+        style.GrabRounding = style.FrameRounding; // Make GrabRounding always the same value as FrameRounding
+    bool window_border = (style.WindowBorderSize > 0.0f);
+    if (ImGui::Checkbox("WindowBorder", &window_border))
+        style.WindowBorderSize = window_border ? 1.0f : 0.0f;
+    ImGui::SameLine();
+    bool frame_border = (style.FrameBorderSize > 0.0f);
+    if (ImGui::Checkbox("FrameBorder", &frame_border))
+        style.FrameBorderSize = frame_border ? 1.0f : 0.0f;
+
     // Save/Revert button
     if (ImGui::Button("Save Ref"))
         *ref = ref_saved_style = style;
@@ -1902,19 +1909,25 @@
     if (ImGui::TreeNode("Settings"))
     {
         ImGui::SliderFloat2("WindowPadding", (float*)&style.WindowPadding, 0.0f, 20.0f, "%.0f");
-        ImGui::SliderFloat("WindowRounding", &style.WindowRounding, 0.0f, 16.0f, "%.0f");
-        ImGui::SliderFloat("ChildRounding", &style.ChildRounding, 0.0f, 16.0f, "%.0f");
         ImGui::SliderFloat("PopupRounding", &style.PopupRounding, 0.0f, 16.0f, "%.0f");
         ImGui::SliderFloat2("FramePadding", (float*)&style.FramePadding, 0.0f, 20.0f, "%.0f");
-        ImGui::SliderFloat("FrameRounding", &style.FrameRounding, 0.0f, 16.0f, "%.0f");
         ImGui::SliderFloat2("ItemSpacing", (float*)&style.ItemSpacing, 0.0f, 20.0f, "%.0f");
         ImGui::SliderFloat2("ItemInnerSpacing", (float*)&style.ItemInnerSpacing, 0.0f, 20.0f, "%.0f");
         ImGui::SliderFloat2("TouchExtraPadding", (float*)&style.TouchExtraPadding, 0.0f, 10.0f, "%.0f");
         ImGui::SliderFloat("IndentSpacing", &style.IndentSpacing, 0.0f, 30.0f, "%.0f");
         ImGui::SliderFloat("ScrollbarSize", &style.ScrollbarSize, 1.0f, 20.0f, "%.0f");
-        ImGui::SliderFloat("ScrollbarRounding", &style.ScrollbarRounding, 0.0f, 16.0f, "%.0f");
         ImGui::SliderFloat("GrabMinSize", &style.GrabMinSize, 1.0f, 20.0f, "%.0f");
-        ImGui::SliderFloat("GrabRounding", &style.GrabRounding, 0.0f, 16.0f, "%.0f");
+        ImGui::Text("BorderSize");
+        ImGui::SliderFloat("WindowBorderSize", &style.WindowBorderSize, 0.0f, 1.0f, "%.0f");
+        ImGui::SliderFloat("ChildBorderSize", &style.ChildBorderSize, 0.0f, 1.0f, "%.0f");
+        ImGui::SliderFloat("PopupBorderSize", &style.PopupBorderSize, 0.0f, 1.0f, "%.0f");
+        ImGui::SliderFloat("FrameBorderSize", &style.FrameBorderSize, 0.0f, 1.0f, "%.0f");
+        ImGui::Text("Rounding");
+        ImGui::SliderFloat("WindowRounding", &style.WindowRounding, 0.0f, 14.0f, "%.0f");
+        ImGui::SliderFloat("ChildRounding", &style.ChildRounding, 0.0f, 16.0f, "%.0f");
+        ImGui::SliderFloat("FrameRounding", &style.FrameRounding, 0.0f, 12.0f, "%.0f");
+        ImGui::SliderFloat("ScrollbarRounding", &style.ScrollbarRounding, 0.0f, 12.0f, "%.0f");
+        ImGui::SliderFloat("GrabRounding", &style.GrabRounding, 0.0f, 12.0f, "%.0f");
         ImGui::Text("Alignment");
         ImGui::SliderFloat2("WindowTitleAlign", (float*)&style.WindowTitleAlign, 0.0f, 1.0f, "%.2f");
         ImGui::SliderFloat2("ButtonTextAlign", (float*)&style.ButtonTextAlign, 0.0f, 1.0f, "%.2f"); ImGui::SameLine(); ShowHelpMarker("Alignment applies when a button is larger than its text content.");