Fix minor error in doc ...

Not a big deal.

Internals: Popup: Moved popup/menu/tooltip positioning code (viewport branch needs it organized in a different manner, so we are pushing the bulk of it here to minimize differences).

Internals: Window: Aggregating ImDrawList into the ImGuiWindow structure.

Settings: Fixed saving an empty .ini file if CreateContext/DestroyContext are called without a single call to NewFrame(). (#1741)

NewFrame: Prevent division by zero in frame rate calculation if io.DeltaTime is continuously zero. (#1740, #881)

Begin: moved tooltip position code in an else block. Misc comments

Internals: Renamed GetFrontMostModalRootWindow() to GetFrontMostPopupModal() and exposed in imgui_internal.h (#1738)

Misc: IM_DELETE() helper function added in 1.60 doesn't clear the input _pointer_ reference, more consistent with expectation and allows passing r-value.

Examples: Added missing calls for ::DestroyWindow, glfwDestroyWindow() + fix old comments.

Version 1.61 WIP

Version 1.60 (missed the string). Will retag.

Fixed erroneous call to io.Fonts->ClearInputData() + ClearTexData() that was left in DX10 example but removed in 1.47 (Nov 2015) in every other back-ends. (fixes 6cee2fc) (#1733, ~#1731) + assert

Nav: Fixed comment. (#1599)

Version 1.60

Internals: Removed unused internal variant of ArrowButton().

Fixed a few zealous warnings.

Fixed unused variable warning.

Style: Default style is now StyleColorsDark()! Toward a 1.60 release :) (#707)

IO: ImGuiConfigFlags_NoMouse disable hovering so it is not destructive. Amend 2464e62

NewFrame: Extract some code into a NewFrameUpdateHoveredWindowAndCaptureFlags() which can be of use with touch-based inputs systems.

Comments about io.WantCapture flags + todo entries.

NewFrame: Extract some code into a NewFrameUpdateMouseInputs function. Moved settings saving higher up in the function so it is next to its peers.

IO: Added ImGuiConfigFlags_NoMouse to force clear/disable mouse inputs in NewFrame().

Renamed ImGuiConfigFlags_NoSetMouseCursor to ImGuiConfigFlags_NoMouseCursorChange. Followup to 75c3793 two weeks ago. (#787, #1495, #1202) + comments

Columns: Fixed calling Columns() again with the same number of columns. (#125)

Contribution guidelines

Hide new windows for one frame until they calculate their size. Also fixes SetNextWindowPos() given a non-zero pivot. (#1694)

Internal: using more consistent comparaison with HiddenFrames to not imply it could be -1. Tweaked comments.

Added extra comments and assertions to avoid user combining ImGuiCond flags. (#1694)

Tooltip windows uses PopupBorderSize (#1697) + commented out debug stuff.