Docking: Wrapping tab bar creation/destroy to make it easier to debug them.

Docking: Fixed crash with ImGuiDockNodeFlags_AutoHideTabBar flag. (#2423, #2109)

Merge branch 'master' into docking ...

# Conflicts:
#	docs/CHANGELOG.txt
#	examples/imgui_impl_opengl3.cpp
#	imgui.cpp
#	imgui_internal.h

IsWindowHovered() made change which should have no effect in master but fix result of IsWindowHovered(ImGuiHoveredFlags_ChildWindows) over multiple viewport in docking branch. (#2432)

Docking: BeginDocked() doesn't need to rely on tab bar data (will allow removing tab bar).

Docking: Preserve existing docked nodes when setting the ImGuiDockNodeFlags_NoDockingInCentralNode flag. (#2423, #2109)

Comments, todo list, remove trailing spaces.

Viewports: Fixed being unable to refocus windows when ConfigViewportsNoTaskBarIcon + ConfigViewportsNoDecoration are enabled. (#2420, #1542) [@PathogenDavid] + comments.

GetMouseDragDelta(): also returns the delta on the mouse button released frame. Verify that mouse positions are valid otherwise returns zero. Removed obsolete comment. Tweaked demo. (#2419)

Version 1.70 WIP

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

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

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.

Moved placeholder sections to match Docking branch. Comments.

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)

Refactor: Move viewport code under other subsystem to simplify merging (3) (moving in multiple commits to make diff/patch behave nicely)

Refactor: Move viewport code under other subsystem to simplify merging (2) (moving in multiple commits to make diff/patch behave nicely)

Refactor: Move viewport code under other subsystem to simplify merging (1) (moving in multiple commits to make diff/patch behave nicely)

Internal: Columns: Allow to use BeginColumns(1) so code designed for variable number of columns can still call NextColumn etc. (#125)