Contents size is preserved while a window collapsed. Fix auto-resizing window losing their size for one frame when uncollapsed.

Added BETA api for Tab Bar/Tabs widgets. (#261, #351) (merged this feature from the from Docking branch so it can be used earlier as as standalone feature) ...

- Added BeginTabBar(), EndTabBar(), BeginTabItem(), EndTabItem(), SetTabItemClosed() API.
- Added ImGuiTabBarFlags flags for BeginTabBar().
- Added ImGuiTabItemFlags flags for BeginTabItem().
- Style: Added ImGuiCol_Tab, ImGuiCol_TabHovered, ImGuiCol_TabActive, ImGuiCol_TabUnfocused, ImGuiCol_TabUnfocusedActive colors.
- Demo: Added Layout->Tabs demo code.
- Demo: Added "Documents" example app showcasing possible use for tabs.

Added ImGuiWindowFlags_UnsavedDocument window flag to append '*' to title without altering the ID, as a convenience to avoid using the ### operator. (merged from Docking branch)

Using named flags instead of 0 + shallow formatting tweaks from other branches.

Added io.ConfigWindowsMoveFromTitleBarOnly option. Still is ignored by window with no title bars (often popups). This affects clamping window within the visible area: with this option enabled title bars need to be visible. (#899) ...

Tweaked default value of style.DisplayWindowPadding from (20,20) to (19,19) so the default style as a value which is the same as the title bar height.

Renamed io.ConfigResizeWindowsFromEdges to io.ConfigWindowsResizeFromEdges and removed its [Beta] mark. Resizing windows from edge is now enabled by default (io.ConfigWindowsResizeFromEdges=true). Note that it only works _if_ the back-end sets ImGuiBackendFlags_HasMouseCursors, which the standard back-end do.

Tests: Adding imgui-test engine hooks (experimental) to provide missing widget state to the testing system.

Internals: Nav: Added ImGuiNavLayer_ to clarify semantic of previously integer NavLayer values, and not pretend that increment/decrement operators on them super flexible. + Storage tweaks.

Comments, tweak

Version 1.67 WIP (again, this time IMGUI_VERSION_NUM has leeway for another hot-fix).

Version 1.66b (will revisit how to change IMGUI_VERSION_NUM across versions, this commit reduces the numerical IMGUI_VERSION_NUM compared to the commit on Nov 22).

About, IO: Added io.BackendPlatformName, io.BackendRendererName for informational/QA purpose.

Added ShowAboutWindow(), About Window now showing various config/build information.

When the focused window become inactive don't restore focus to a window with the ImGuiWindowFlags_NoInputs flag. (#2213)

Added ImGuiConfigFlags_None, ImGuiBackendFlags_None for good measure.

Version 1.67 WIP

Version 1.66

Nav: Fixed explicit directional input not re-highlighting current nav item if there is a single item in the window and highlight has been previously disabled by the mouse. (#787)

Internals: Using GetOverlayDrawList(ImGuiWindow*) to match syntax of viewport/master branches. Fixed compiling with IMGUI_DEBUG_NAV_RECTS

Removed unnecessary ImGui:: prefixes.

Internals: Added FindWindowByID() helper. (#2190)

Nav: Fixed an assert in certain circumstance (mostly when using popups) when mouse positions stop being valid. (#2168) + adding a else block to make NavCalcPreferredRefPos() more explicit.

Made IsWindowFocused() work outside of NewFrame()-EndFrame() and added comments about how ImGuiFocusedFlags_AnyWindow should NOT be used in place of io.WantCaptureMouse. (#2185)

Config: Added IMGUI_DISABLE_WIN32_FUNCTIONS to disable linking with _any_ Win32 function, as a general forward compatible measure.

Doc: Fixed comments referring to LoadFromFileTTF() instead of AddFontFromFileTTF() (#2153)

Fixed OpenGL texture loading example in comment + Discourse link to root of discourse

Misc comments improvements

Comments in demo and opengl code + Internals: Added HoveredIdNotActiveTimer tracking hovering time unless the item is active, which is a commonly useful pattern.

Added ImGuiWindowFlags_NoMouseInputs which is basically the old ImGuiWindowFlags_NoInputs (essentially we have renamed ImGuiWindowFlags_NoInputs to ImGuiWindowFlags_NoMouseInputs). Made the new ImGuiWindowFlags_NoInputs encompass both NoMouseInputs+NoNav, which is consistent with its description. (#1660, #787)

Window: Added ImGuiWindowFlags_NoBackground flag for consistency and to ease creating new flag combinations. Added ImGuiWindowFlags_NoDecoration helper flag which is essentially NoTitleBar+NoResize+NoScrollbar+NoCollapse. (#1660)