Internal: Extracted some of the Begin code into RenderWindowTitleBarContents().

Internal: Begin: Update rectangles before Scrollbar() which now uses them. Fixes 39eeda0.

Internal: Scrollbar: Further sane simplification (using InnerMainRect instead of duplicating calculations).

Internal: Scrollbar: Extracted scrollbar code for other uses (eg. table v2 scrolling without using a child window).

Separator: Revert 1.70 "Declare its thickness (1.0f) to the layout" change (c5d83d8a). It's not incorrect but it breaks existing some layout patterns. Will return back to it when we expose Separator flags.

Internals: Columns: Renamed fields. Comments and tweak. Moved a demo block.

Internal: Refactored Separator into SeparatorEx(), exposed ImGuiSeparatorFlags_SpanAllColumns in imgui_internal.h and support without. (#759) + misc comments

Columns: Fixed Separator from creating an extraneous draw command. Fixed Selectable with SpanAllColumns flag from creating an extraneous draw command. (#125)

Version 1.71 WIP + fixed minor typo

Version 1.70

Examples: DirectX9/10/11: Taking reference to device + subsequent merge of this in docking will fix DX9 issue #2524

Examples Readme and Changelog tweaks, added #2527, re-ordered examples/README alphabetically.

Examples: Metal: Add GLFW+Metal example

Window: Fixed SetNextWindowSizeConstraints() with non-rounded positions making windows drift. (#2067, #2530)

Misc: Made IMGUI_CHECKVERSION() macro also check for matching size of ImDrawIdx.

Internals: Fixed incorrect repeat delay/rate calculation in IsMouseClicked() with repeat flag leading to involontary but thankfully doubling the rate. Using our standard function, making the multiplicator explicit.

Selectable: With ImGuiSelectableFlags_AllowDoubleClick doesn't return true on the mouse button releas efollowing the double-click. Only first mouse release + second mouse down (double-click) returns true. Likewise for internal ButtonBehavior() with both _PressedOnClickRelease | _PressedOnDoubleClick. (#2503)

Demo: Improved trees in columns demo. (#2136)

Internals: Rename GetContentRegionMaxScreen() -> GetWorkRectMax(). At this point this is mostly useful to facilitate merge of other branches.

Internals: SettingsHandlerWindow_ReadLine uses context parameter.

Examples: Added missing per-renderer local changelogs. (#2037, #1639, #2452)

ImDrawCallback_ResetRenderState: Added Metal.

ImDrawCallback_ResetRenderState, Examples: Added support for reset render state callback. (#2037, #1639, #2452)

Obsoleted GetContentRegionAvailWidth(), use GetContentRegionAvail().x instead. Kept inline redirection function.

Drag and Drop: Fixed drag source with ImGuiDragDropFlags_SourceAllowNullID and null ID from receiving click regardless of being covered by another window (it didn't honor correct hovering rules). (#2521)

Amend 48a09a7 with changelog, breaking changes, tweak demo code for spacing. (#2518)

Improved algorithm for mitre joints on thick lines

Tidying up BeginMenu() code + comments.

Popups: Closes popup at the time of FocusWindow(). Fixes right-click from closing all popups instead of aiming at the hovered popup level (regression in 1.67's ae76a1fd).

Popups: Closing a popup restores the focused/nav window in place at the time of the popup opening, instead of restoring the window that was in the window stack at the time of the OpenPopup call. (#2517) ...

Among other things, this allows opening a popup while no window are focused, and pressing Escape to clear the focus again.