Internals: DrawData: renamed fields only (committing separately so that next commit is less nosiy).

MovingWindow: Track click offset based on MovingWindow and not its RootWindow. Followup to 3849bb4. Comments + adding a local to ease patch #1345.

Fix cross compilers

Internals: Merge of harmless stuff from Navigation stuff. Added GetHoveredID() internal helper.

Begin: FIx previous commit - no need to call on collapsed window. Handle manual resize (grip, border, gamepad) before setting up window DrawList main clipping rectangle. Sane (and required for viewport code). (#822, #1542)

Begin: Handle manual resize (grip, border, gamepad) before setting up window DrawList main clipping rectangle. Sane (and required for viewport code). (#822, #1542)

MovingWindow: Proper fix for 651538e attempt, without altering MovingWindow which has side-effects. Clicking on a window with the ImGuiWIndowFlags_NoMove flags takes an ActiveId so we can't hover something else. (ref #1381, #1337)

Revert "Clicking on a window with the ImGuiWIndowFlags_NoMove flags takes an ActiveId so we can't hover something else. (ref #1381, #1337)" ...

This reverts commit 651538e.

Begin: Shuffling bits of code around.

Clicking on a window with the ImGuiWIndowFlags_NoMove flags takes an ActiveId so we can't hover something else. (ref #1381, #1337)

Added ImGuiHoveredFlags_AnyWindow, ImGuiFocusedFlags_AnyWindow. Obsoleted IsAnyWindowHovered()/IsAnyWindowFocused() in favor of IsWindowHovered(ImGuiHoveredFlags_AnyWindow)/IsWindowFocused(ImGuiFocusedFlags_AnyWindow). Added to demo. (#1382)

Internals: Begin: Refactor some code into an UpdateManualResize() function.

Internals: Begin: Moved DrawList setup code below, the viewport system will need to push the outer clipping rectangle as late as possible.

Begin: Moving some code around for the benefits of the wip viewport branch.

Internals: Using ImFloor().when appropriate.

InputText: Added alternative clipboard shortcuts: Shift+Delete (cut), Ctrl+Insert (copy), Shift+Insert (paste). (#1541)

InputText: Moved code for checking clipboard shortcut so we can expand on it. (#1541)

Popups: Comments, reorganize bits of the header section, renamed parameters.

BeginPopup: Exposed extra_flags publicly. (#1533)

OpenPopup(): Always reopen existing popup. Removed OpenPopupEx() bool reopen_existing which is always true. This also makes the public API on par with OpenPopupEx(). (#1497, #1533)

Popups: Gently handle the user mistakenly calling OpenPopup() every frame. (when reopen_existing is true). (#1497)

Internals: Popup: Renaming fields.

Popup, Menus: Tweaks and comments.

Internals: Popup: Explicitely setting up ImGuiPopupRef reduces confusion.

Popups: Revert aca23fd (Oct 20, 2017). Because 1) I can't seem to find a default. 2) The if is definitively faulty and would have been all true. 3) It looks like possibly the following commit 6ab737a could have made this unnecessary. Not absolutly certain. (~#439)

Popup: BeginPopupContextItem(), BeginPopupContextWindow(), BeginPopupContextVoid(), OpenPopupOnItemClick() all react on mouse release instead of mouse click. Note that they don't use the full ButtonBehavior() or tracking aabb on both click and release. Applications I've tried seems to behave inconsistently there but on-release-without-tracking is both fairly common and doesn't require extra code for the id tracking. (~#439)

Internal: ButtonBehavior: Tweak to update g.ActiveIdClickOffset more consistently

Internal: Reworked FocusFrontMostActiveWindow() so it fits the Nav branch usage as well.

Internals: Popup: Separating MousePosOnOpen and PopupPosOnOpen. They are equal in the master branch but different in the navigation branch.

Internals: renamed FocusPreviousWindow() to FocusfrontMostActiveWindow()