Popups: fixed CloseInactivePopups() so that right-clicking to close one level of popups in a popups stack won't close the whole stack. This is done by properly refocusing the lower level popup. Fixes 87ae408 (~#439)

Added OpenPopupOnItemClick(); helper which mimic BeginPopupContextItem() but doesn't do the open. ...

Made the color popups uses this standard function so they handle reopening a context menu.

BeginPopupContextItem(), BeginPopupContextWindow(): Using newly introduced IsItemHovered() flags to allow reopening another context menu (over same or not same item) with right-click. (#439) (+1 squashed commits)

IsWindowHovered(): Changed default behavior to now return false is a widget from another window is active + Added support for ImGuiHoveredFlags_AllowWhenBlockedByActiveItem. (relate to drag'n drop idoms: #143)

IsItemHovered(), IsWindowHovered(): added flags to enable various and more specific behavior. Will enable improvements for popups/context menus and drag'n drop. (relate ~#439, #1013, #143, #925) ...

The legacy confusing IsItemRectHovered(), IsWindowRectHovered() can be completely removed now.
Changed IsWindowHovered() behavior with default parameter: it now return false is the window is blocked by a popup.
Demo: Added tests for those two functions.

Moved IMGUI_DISABLE_OBSOLETE_FUNCTIONS block lower in the imgui.h file so obsolete functions can use flags. Also sane to quarantine them outside of the respectable area.

Made the ImGuiWindowFlags_NoMove flag inherited from parent to child, so in a setup with RootWindow (no flag) -> Child (NoMove flag) -> SubChild (no flag) user won't be able to move the root window by clicking on SubChild. (#1381)

Fixed a bug allowing to move a _NoMove window from a child that doesn't have the flag. (#1381) ...

broken by e56eba4 (#1337)

Popups: popups can be closed with a right-click anywhere, without altering focus under the popup.(~#439)

Popups: Fixed a bug introduced in 1a35766 which made the BeginPopupContextXXX functions create popups without border. (nb: all that border mess is going away in styling clean up)

Refactor EndFrame() code that process focusing window with left mouse button. This commit should be no-op.

Internals: PaintVerts** renamed to ShadeVerts**, moved to imgui_draw.cpp and exposed in imgui_internal.h (+1 squashed commits)

Documentation: Extra comments + tweaks to make usage of long-line more bearable.

Internals: RenderCollapseTriangle() -> RenderTriangle(), takes a ImGuiDir

CollapsingHeader(bool*) variant: fixed for IsItemHovered() to work properly in the nav branch.Basically the close button now has to use ItemAdd() to be navable into, which overwrite the IsItemHovered data. (#600, #787)

Internals: ButtonBehavior: made ImGuiButtonFlags_PressedOnClick and ImGuiButtonFlags_PressedOnDoubleClick set the click offset correctly + hold on g.ActiveId so Held state can be reported. Added ImGuiButtonFlags_NoHoldingActiveId flag to disable the later.

Checkbox: Using checkmark. MenuItem: Tweaked checkmark, thicker.

Begin: Marked 5 parameters version of Begin() as obsolete. Now waiting for a riot to happen!

Begin: Work toward obsoleting the 5-arguments Begin() overload. Internal BeginEx() becomes the normal public Begin() again! (4)

Begin: Work toward obsoleting the 5-arguments Begin() overload. Removed bg_alpha from internal BeginEx(). (3)

Begin: Work toward obsoleting the 5-arguments Begin() overload. Removed size_on_first_use from internal BeginEx(). (2)

Begin: Work toward obsoleting the 5-arguments Begin() overload. (1)

BeginPopupContextItem() now supports a NULL string identifier and uses the last item ID if available. For interactive items (that have an ID) this works! For non interactive items we assert.

Fix IsItemHovered() issue on child by temporarily reverting 344d48b. This is not the ideal solution. (Fix #1370)

Removed apparently unncessary code in InputFloatN() and InputInt().

Exposed Scrollbar() in imgui_internal.h and removed a bool arg

Rnamed AlignFirstTextHeightToWidgets() to AlignTextToFramePadding(). Kept inline redirection function (will obsolete).

TreeNode: Added ImGuiTreeNodeFlags_FramePadding flag

Internal: ItemAdd(), IsClippedEx(): removed unnecessary indirection for ID parameter

Removed extraneous calls to GetCurrentWindowRead() when we already have a ImGuiContext. Internal RenderXXX functions also don't need to write into the Accessed field at all.