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()

Internals: BringWindowToFront() iterate front to back, faster in majority of use cases.

Revert "Internals: Added LastActiveId, LastActiveIdTimer. (#1537)" Will come up with a better design later. ...

This reverts commit 007f403.

Internals: Added LastActiveId, LastActiveIdTimer. (#1537)

Merge of minor left-overs from private work branch to reduce drifts. Should be functionally a no-op.

Fixed non-popup child windows not honoring the HiddenFrames flag (can't see a reason). Docking relies on this.

Internals: Settings api tweaks

DragDrop: Removed IsDragDropActive() (introduced a few days ago, revert 06bea36) as our use case doesn't need it anymore. Will add it if there is a real need.

Columns: Clear offsets data when columns count changed. (#1525)

Internals: Renamed ImGuiSimpleColumns to ImGuiMenuColumns to avoid confusion. Reduced internal buffer size (we only use 3 slots).

Casing tweaks + clarify license copyright (simpler/safer?) (#1346)

Renamed ImGuiSizeConstraintCallback to ImGuiSizeCallback, ImGuiSizeConstraintCallbackData to ImGuiSizeCallbackData.

Internals: NextWindow: Renamed, moved functions to member.

Internals: NextWindow: Using ImGuiCond for consistency.

Internals: refactored g.SetNextWindow fields into g.NextWindow. structure (so it can be more easily transported/copied)

Fix a memory leak of ImGuiColumnsSet's Columns vector. ImVector doesn't call destructors.

Internals: NewFrame: Shuffled some code around (to minimize upcoming patches)

Removed CalcItemRectClosestPoint() which was weird and not really used by anyone except demo code. If you need it it's easy to replicate on your side. ...

Removed internal corresponding ImRect::GetClosestPoint() for now.
Essentially revert dcaafff.

MenuBar: Fixed menu bar pushing a clipping rect outside of its allocated bound (usually unnoticeable).

Demo: Tweak. Comments. Metrics: Added some Drag and Drop info.