Debug Tools: Added DebugStartItemPicker() in imgui_internal.h to facilitate binding this anywhere in user's tool. Adedd highlight. Added IMGUI_DEBUG_TOOL_ITEM_PICKER_EX to break in ItemAdd().

Internals: Refactor: Moved all Columns code from imgui.cpp to imgui_widgets.cpp (#125) ...

Also moved NextColumn between BeginColumn and NextColumn which makes it easier to work on that code.

Fixed old SetWindowFontScale() api value from not being inherited by child window. Added comments about the right way to scale your UI (load a font at the right side, rebuild atlas, scale style). ...

+ Added missing IMGUI_API marker to the EmptyString storage used by ImGuiTextBuffer. (#2672)

Debug, Metrics: Added "Tools->Item Picker" tool which allow clicking on a widget to break in the debugger within the item code. The tool calls IM_DEBUG_BREAK() which can be redefined in imconfig.h if needed.

Moved ImGuiColumnsFlags erroneously forward declared in imgui.h + demo bit.

Internals: Checkbox: Added undocumented mixed/indeterminate/tristate support via ImGuiItemFlags_MixedValue. (#2644)

Internals: Renamed GetFrontMostPopupModal() to GetTopMostPopupModal() to be consistent. Renamed other locals to follow that terminology.

Internals: Columns: Poke into WorkRect and use them in the GetContentRegionMax() functions. This should be a no-op, but preparing us to transition toward using WorkRect instead of ContentRegionRect. ...

Removed one use of ContentsRegionRect.

Disable -Wpragmas warning in GCC to avoid relying on version checks, as unusual/forks/mods don't appear to always have same warning<>version. (#2618) ...

+ Fix version number in imgui.h

Version 1.72 WIP

Version 1.71 + comments

Readme, comments, dear imgui prefixes

Log/Capture: Fixed BeginTabItem() label not being included in a text log/capture. ...

Extracted tab rendering code into a RenderTextEllipsis() function.

Internals: Added drawlist and color arg to RenderArrow(), RenderBullet(). Reordered args for RenderPixelEllipsis.

imgui-test: Added IMGUI_TEST_ENGINE_LOG macro to emit into test log from core or user land.

Made PushID() behave the same in 32-bit and 64-bit, by not padding the integer into a void*. (Also technically faster.)

Synced/merged minor cruft from docking branch to minimize drift. AFAIK the only meaningful no-op change is that the call UpdateHoveredWindowAndCaptureFlags() was moved above UpdateMouseMovingNewFrame() to match what docking branch has been doing for a while.

Internals: Storing ScrollMax into a member. Mostly to facilitate debugging. Also locking down window->Scroll slightly lower in the Begin function.

Internals: Renamed SizeContents to ContentSize, SizeContentsExplicit to ContentSizeExplicit. Tweaked Metrics->Show Rectangles functionality.

Window rectangles: Changed WorkRect to cover the whole region including scrolling (toward obsolete ContentsRegionRect) + using full WindowPadding*1 padding. ...

Tweaked InnerClipRect.
TreeNode, CollapsingHeader: Fixed highlight frame not covering horizontal area fully when using horizontal scrolling. (#2211, #2579)
TabBar: Fixed BeginTabBar() within a window with horizontal scrolling from creating a feedback loop with the horizontal contents size.
Columns: Fixed Columns() within a window with horizontal scrolling from not covering the full horizontal area (previously only worked with an explicit contents size). (#125)
Demo: Added demo code to test contentsrect/workrect

Clarified behavior of SetNextWindowContentSize(). Content size is defined as the size available after removal of WindowPadding on each sides. So SetNextWindowContentSize(ImVec2(100,100)) + auto-resize will always allow submitting a 100x100 item without creating a scrollbar, regarding of WindowPadding.The exact meaning of ContentSize for decorated windows was previously ill-defined.

Nav: Fixed gamepad/keyboard moving of window affecting contents size incorrectly, sometimes leading to scrollbars appearing during the movement. + minor fix with the mostly dead Ctrl+wheel scaling.

Internals: Window rectangles: Renaming of all rectangles toward their final form. Should be a no-op. Renamed GetWorkRectMax() to GetContentRegionMaxAbs(). Metrics shows SizeContents.

ImDrawList: Store initial flags for the frame in ImDrawListSharedData, reducing code duplication in setting up the flags.

CollapsingHeader: When a close button is enabled, better clip the label to avoid overlap. (#600)

Internal: Renamed InnerMainRect to InnerVisibleRect. Printing coordinates in Metrics window.

Comments, todo entries, moved ImGuiSelectableFlagsPrivate in higher ranges to match others.

Internal: CloseButton takes an upper-left corner + a size to be consistent with similar widgets.

Internals: Extracted some of the tab bar shrinking code into a ShrinkWidths() function so columns/table can use it.

Internals: Added InnerWorkRect equal to old InnerClipRect, added InnerWorkRectClipped actually clipped.