Combo: Removed ImGuiWindowFlags_ComboBox flag. Moved internal window flags.

Mouse wheel scrolling doesn't change speed inside Combo box (uses to slow down from 5 to 3) but instead slow down on window that are smaller than the scroll speed.

Combo: Cleanup. Removed unrequired uses of the _ComboBox flag (the test in EndChild() is from commit no 1!). We could remove ImGuiWindowFlags_ComboBox soonish.

Standardizing the casing/format of internal window names + Misc comments.

Combo: Recycling windows by using a stack number instead of a unique id, wasitng less windows.

Combo: Moved functions (untouched).

Combo: Added flags to BeginCombo() new api, removed explicit height, default to 8 instead of 7 items, allow popup height constraints via SetNextWindowSizeConstraints(), width expand if contents doesn't fit, popup reposition policy if it doesn't fit.

Internals: Renamed CalcSizeFullWithConstraint() to CalcSizeAfterConstraint() which is more appropriate + added explicit parameter to CalcSizeAutoFit() so it can be used externally.

Fixed scrollbar issue, source size when explicit was read before applying custom size constraints (followup to cc2c023 etc.)

Combo: Comments + fixed missing lower window padding.

Internals: Renamed FindBestPopupWindowPos() to FindBestWindowPosForPopup()

IsItemHovered() comments (#1382)

Begin: Factored out a bit of code to CalcSizeContents()

Begin: Remove unnecessary usage of window_is_new flag, as both fields are zero on window creation.

Internals: BeginCombo() added dummy ImGuiComboFlags.

Indent(), Unindent(): Allow passing negative values.

Begin: Minor refactor following fcf652f. Merging the if (Collapsed) block with the main one.

Begin: Sizing fixes regarding uses SetNextWindowSize() on individual axises.

Minor tweaks. Using ImGuiAxis defines.

Fixed 64-bit warnings.

Fixed scrollbar issue, followup to beda5fc and 2df8fa9.

Internals: Cleanup FindBestPopupWindowPos() to be more digestible, since we are bounds to rework the logic there. No functional changes intended. FIXED TYPO.

Internals: Cleanup FindBestPopupWindowPos() to be more digestible, since we are bounds to rework the logic there. No functional changes intended

Exposed GetOverlayDrawList(). (~#545, ~#530)

Begin: Move the code that update the Appearing flag above the BeginDocked() branch.

Fixed scrollbar enable/disable calculation when size is modified programmatically. This is the generalization of the fix in 2df8fa9.

Lower-right resize grip only appears when hovered. (#822)

Comments about ImGuiWindowFlags_ResizeFromAnySide. Removed hovering color. May need its own color. (#822)

Windows can be resized from their borders when ImGuiWindowFlags_ResizeFromAnySide is set. (#822) The interaction is currently unsatisfying because we can only reach a window from its inner rectangle (because of HoveredWindow filtering).

Tweak four-corners resize grip code. Added ImRect::FixInverted() helper. (#822)