Revert "Scrollbar: Minor simplication of the code using InnerRect data." > Introduced sheering on the scrollbar rectangle because InnerRect isn't setup at this point. ...

This reverts commit 7ac1583.

Columns: Column width data is no longer lost while dragging toward the right side. (#1499, #125)

Columns: Minor stylistic fixes. (#125)

BeginChild() fix using negative sizes as window position because of erroneous clamping. It was hard to notice until we added asserts for it. (#1500)

Columns: Added internal tracking of a few flag temporarily, to facilitate the work of third-parties who have columns patches. (#125)

Columns: Refactor: Moved ColumnsSet[] to window out of DC as they are persistent data for most + fix for pre C++11 compilers. (#125, #1499)

Columns: Refactor: Not using statestorage lookup anymore. (#125, #1499)

Columns: Refactor: Renamed all members. (#125, #1499)

Columns: Refactor: Moved columns data into their own data structure. Minimum changes now to ease diffing. (#125, #1499)

IsWindowFocused(): oops, that was bound to happen with loosely typed enums (this is sort of why I made both values identical - no direct side effects).

Drag and Drop: Exposed some internals.

Merged miscellaneous small stuff (from nav/dock branches).

Added IsAnyWindowFocused() (from Nav branch).

Merge branch 'drag_and_drop'

Drag and Drop: Fix merge for IMGUI_DISABLE_OBSOLETE_FUNCTIONS

Tweak

Begin: Tidying up code to make it more readable.

Fixed ParentWindow setup which broke Modal windows (fix c65124f)

Drag and Drop: Drop target infer a fallback ID from the rectangle. Avoid Preview being accepted on drop frame when drop target has no ID. (#143)

Drag and Drop: Added ImGuiCol_DragDropTarget (#143, #707)

Drag and Drop: Comments

Merge branch 'master' into drag_and_drop ...

# Conflicts:
#	imgui.cpp
#	imgui.h
#	imgui_internal.h

Renamed GetItemsLineHeightWithSpacing() to GetFrameHeightWithSpacing()

Added GetFrameHeight() function (used to be SmallSquareSize internally)

Internals: Added GetSmallSquareSize()

IsWindowFocused() refactor will flags. (#1382) ...

Marked IsRootWindowFocused() as obsolete in favor of using IsWindowFocused(ImGuiFocusedFlags_RootWindow).
Marked IsRootWindowOrAnyChildFocused() as obsolete in favor of using IsWindowFocused(ImGuiFocusedFlags_RootAndChildWindows).

Internals: ParentWindow is now NULL for non-child windows and means what everyone expects.

Internals: Removed misleading GetWindowParent() function. + renaming to clear confusing.

IsWindowHovered(): split ImGuiHoveredFlags_FlattenChild into separate ChildWindows and RootWindow flags. Allowing more combination and a better symetry with IsWindowFocused() flags. (#1382)

Renamed ImGuiTreeNodeFlags_AllowOverlapMode to ImGuiTreeNodeFlags_AllowItemOverlap. (#600, #1330)