Added a more convenient three parameters version of Begin() which covers the common uses better.
Added mouse cursor types handling (resize, move, text input cursors, etc.) that user can query with GetMouseCursor(). Added demo and instructions in ShowTestWindow().
Added embedded mouse cursor data for MouseDrawCursor software cursor rendering, for consoles/tablets/etc. (#155).
Added first version of BeginPopup/EndPopup() helper API to create popup menus. Popups automatically lock their position to the mouse cursor when first appearing. They close automatically when clicking outside, and inhibit hovering items from other windows when active (to allow for clicking outside). (#126)
Added thickness parameter to ImDrawList::AddLine().
Added style.DisplaySafeAreaPadding which was previously hard-coded (useful if you can't see the edges of your display, e.g. TV screens).
Added CalcItemRectClosestPoint() helper.
Added GetMouseDragDelta(), IsMouseDragging() helpers, given a mouse button and an optional "unlock" threshold. Added io.MouseDragThreshold setting. (#167)
IsItemHovered() return false if another widget is active, aka we can't use what we are hovering now.
Added IsItemHoveredRect() if old behavior of IsItemHovered() is needed (e.g. for implementing the drop side of a drag'n drop operation).
IsItemhovered() include space taken by label and behave consistently for all widgets (#145)
Auto-filling child window feed their content size to parent (#170)
InputText() removed the odd ~ characters when clipping.
InputText() update its width in case of resize initiated programmatically while the widget is active.
InputText() last active preserve scrolling position. Reset scroll if widget size becomes bigger than contents.
Selectable(): not specifying a width defaults to using max of label width and remaining width.
Selectable(const char*, bool) version has bool defaulting to false.
Selectable(): fixed misusage of GetContentRegionMax().x leaking into auto-fitting.
Windows starting Collapsed runs initial auto-fit to retrieve a width for their title bar (#175)
Fixed new window from having an incorrect content size on their first frame, if queried by user. Fixed SetWindowPos/SetNextWindowPos having a side-effect size computation (#175)
InputFloat(): fixed label alignment if total widget width forcefully bigger than space available.
Auto contents size aware of enforced vertical scrollbar if window is larger than display size.
Fixed new windows auto-fitting bigger than their .ini saved size. This was a bug but it may be a desirable effect sometimes, may reconsider it.
Fixed negative clipping rectangle when collapsing windows that could affect manual submission to ImDrawList and end-user rendering function if unhandled (#177)
Fixed bounding measurement of empty groups (fix #162)
Fixed assignment order in Begin() making auto-fit size effectively lag by one frame. Also disabling "clamp into view" while windows are auto-fitting so that auto-fitting window in corners don't get pushed away.
Fixed MouseClickedPos not updated on double-click update (#167)
Fixed MouseDrawCursor feature submitting an empty trailing command in the draw list. Fixed unmerged draw calls for software mouse cursor.
Fixed double-clicking on resize grip keeping the grip active if mouse button is kept held.
Bounding box tests exclude higher bound, so touching items (zero spacing) don't report double hover when cursor is on edge.
Setting io.LogFilename to NULL disable default LogToFile() (part of #175)
Tweak stb_textedit integration to be lenient if another piece of code are leaking their STB_TEXTEDIT definitions/symbols.
Shutdown() freeing a few extra vectors so they don't have to freed by destruction (#169)
Examples: OpenGL2/3 examples automatically hide the OS mouse cursor if software cursor rendering is used.
ShowTestWindow: Added Widgets Alignment demo under Layout section
