Demo: Custom rendering: Minor sizing issue fix.

Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	examples/example_win32_directx10/main.cpp
#	examples/example_win32_directx11/main.cpp
#	examples/example_win32_directx12/main.cpp
#	examples/example_win32_directx9/main.cpp

Version 1.69, comments, typos

Viewport: DestroyPlatformWindow() skips calling user function if PlatformWindowCreated is set. + Clarified comment about implicit Debug viewport which may be hogging a viewport.

Fixed main viewport not being marked as created, which broke updating the IME input position for the main viewport. ...

This change also removes the logic scattered about that compensated for PlatformWindowCreated being wrong for the main viewport.

Internals: Fixed Navigation from reaching ImGuiItemFlags_Disabled items (#211) + Examples comments

TabBar: Reworked scrolling policy (when ImGuiTabBarFlags_FittingPolicyScroll is set) to teleport the view when aiming at a tab far away the visible section, and otherwise accelerate the scrolling speed to cap the scrolling time to 0.3 seconds.

TabBar: Fixed Tab tooltip code making drag and drop tooltip disappear during the frame where the drag payload activate a tab.

Merge branch 'master' into docking ...

# Conflicts:
#	examples/imgui_impl_glfw.cpp
#	examples/imgui_impl_sdl.cpp

Examples: GLFW, SDL: Preserve DisplayFramebufferScale when main viewport is minimized. (This is particularly useful for the viewport branch because we are not supporting per-viewport frame-buffer scale. It fixes windows not refreshing when main viewport is minimized.) (#2416)

Fixed Clang and PVS warnings.

InputText: Fixed c779fbb leading to display of the wrong buffer when resizing a buffer. (#2400, #2006, #1443, #1008).

Demo: InputText: Demonstrating use of ImGuiInputTextFlags_CallbackResize. (#2006, #1443, #1008).

Added GetGlyphRangesVietnamese() helper. (#2403)

Internal: Removed unused fields from ImGuiMenuColumns.

Docking: Fixed node merging altering window position incorrectly in a way that would make SizeContents incorrect for the next frame (making scrollbar flicker). (#2414, #2109)

Viewport: Popups and Tooltips viewports are correctly parented to the parent window's viewport. (#2409, #1542)

Merge branch 'master' into docking ...

# Conflicts:
#	examples/example_win32_directx11/main.cpp
#	examples/example_win32_directx12/main.cpp
#	examples/example_win32_directx9/main.cpp
#	imgui.cpp

Examples: Win32+DirectX: moved helper functions below main.

Viewports: Fixed delayed window pos->viewport pos sync leading to monitor not being updated at the time of clamping window position in Begin. (#2415, #1542)

Viewports: Renamed ConfigViewportsNoParent to ConfigViewportsNoDefaultParent. Fix outdated comments in examples.

Docking: Fixed an issue where removing the last window from a dockspace node that is not a central node without remove the node. (#2414, #2109)

Fix typos. (#2413)

Don't use const qualified parameters in declarations. ...

This fixes warnings from clang-tidy like this:

    parameter 'v_max' is const-qualified in the function declaration;
    const-qualification of parameters only has an effect in function definitions

Since values (rather than references or pointers) don't need to be
const, they don't need to be marked that way in the function declaration.

Added ImGuiColorEditFlagsFlags_InputHSV. (#2383, #2384)

ColorEdit: Fixed tooltip not honoring the ImGuiColorEditFlags_NoAlpha contract of never reading the 4th float in the array (value was read and discarded). (#2384)

Moved placeholder sections to match Docking branch. Comments.

Fix typos. (#2411)

Merge branch 'master' into docking

Refactor: Move viewport code under other subsystem to simplify merging (4) (moving in multiple commits to make diff/patch behave nicely)