Fix 61d9258 when there is not scrollbar "Window: Fixed contents region being off by WindowBorderSize amount on the right when scrollbar is active."

Internals: Renaming. Renamed ImGuiPopupRef to ImGuiPopupData for consistency and added constructor.

Internals: Begin: Moved OuterRectClipped/InnerMainRect/InnerClipRect computation higher up in the function, next to ContentsRect/WorkRect code. Removed commented out debug drawing code which is now available in Metrics window.

Window: Fixed contents region being off by WindowBorderSize amount on the right when scrollbar is active.

Internals: Nav scrolling uses InnerMainRect instead of InnerClipRect.

Internals: TempInputText: Rename InputScalarAsWidgetReplacement() -> TempInputTextScalar(), ScalarAsInputTextId -> TempInputTextId, small tidying up in affected functions.

Internals: Using more explicit PushOverrideID() helper + renamed equivalent internal tree helper.

Window: Fixed window with the AlwaysAutoResize flag unnecessarily extending their hovering boundaries by a few pixels (this is used to facilitate resizing from borders when available for a given window). One of the noticeable minor side effect was that navigating menus would have had a tendency to disable highlight from parent menu items earlier than necessary while approaching the child menu. ...

+ Changelog fixed unfinished sentence and tweaks,

MenuItem, BeginMenu: Fix undesirable tall frames in horizontal layout context, which would be visible when trying to use rounded selectable/menus. ...

PushStyleVar: Added comments in the assert message.
Minor tweaks.

Misc comments, internal renaming, added disable indentation option to Columns demo section.

Internals: ImHashStr() default parameter.

Added SetNextItemWidth() helper to avoid using PushItemWidth/PopItemWidth() for single items.

Misc: Fixed PushItemWidth(-width) (for right-side alignment) laying out certain items (button, listbox, etc.) with negative sizes if the 'width' argument was smaller than the available width at the time of item submission,

Internals: Rework CalcItemWidth / CalcItemSize but make their similarities and their differences more obvious. (#2449)

Added commentary about ContentRegion functions. Added internal GetContentRegionMaxScreen() to facilitate internal code at the moment.

Internals: Moved CalcItemSize next to CalcItemWidth, added comments to clarify their respective intent. Should have no side effect.

Internals: Columns: Tweaks, renaming. Metrics: Show rectangles for child windows. ...

Renamed SameLine() first parameter.

Columns: Fixed boundary of clipping being off by 1 pixel within the left column.

Clarified asserts comments + todo entries. (#2500)

Metrics: Added "Show windows rectangles" tool to visualize the different rectangles.

Merged a bunch of small changes from Docking branch to reduce the difference between branches. ...

Noticeable: horizontal alignment of CloseButton. Menu fill take account of border. Various stylistic tweaks to accomodate other changes in Docking.

Internals: Columns: Some renaming, extracted code into GetColumnsID().

Internals: Moved resize grips and borders to nav layer 1 so that testing system doesn't attempt to scroll to get them inside the InnerRect.

Tests: Added hook/tweaks for imgui-test engine. + Fixed warnings.

Internals: Merge minor things from range_select branch. Added ImGuiButtonFlags_NoHoveredOnNav. Added IsItemToggledSelected() - unused here. Renaming.

FAQ tweaks. Add missing entries in imgui.cpp (which until now where only in the README).

Misc: Added IM_MALLOC/IM_FREE macros mimicking IM_NEW/IM_DELETE so user doesn't need to revert to using the ImGui::MemAlloc()/MemFree() calls directly.

Tabs to Spaces, comments.

InputText: Work-around for buggy standard libraries where isprint('\t') returns true. (#2467, #1336) ...

Not using isprint. + todo items.

Internals: Renamed the ImGuiWindow HiddenFrameXXX fields to decorrelate them from resizing behavior, as those values are set by other logic.