Moved placeholder sections to match Docking branch. Comments.

Internal: Columns: Allow to use BeginColumns(1) so code designed for variable number of columns can still call NextColumn etc. (#125)

Fixed IsItemDeactivated()/IsItemDeactivatedAfterEdit() from not correctly returning true when tabbing out of a focusable widget (Input/Slider/Drag) in most situations. (#2215, #1875) ...

+ Minor renaming of a local variable in widget code.

Internal: Tabbing/Focus: Tidying up old code, moved some state to context instead of window. Storing new data will allow us to fix the bug mentioned in #2215 (probably in next commit).

Internal: Tabbing: Tweaks to FocusableItemRegister and using the standard mechanism to allow/block Tab being interpreting by tabbing instead of InputText() widget.

Nav: Fixed Ctrl+Tab keeping active InputText() of a previous window active after the switch. (#2380)

Renamed GetOverlayDrawList() to GetForegroundDrawList() for consistency. Kept redirection function (will obsolete). (#2391) ...

Demo: Using GetBackgroundDrawList() and GetForegroundDrawList() in "Custom Rendering" demo.

Added GetBackgroundDrawList() helper to quickly get access to a ImDrawList that will be rendered behind every other windows. (#2391)

Misc: Asserting in NewFrame() if style.WindowMinSize is zero or smaller than (1.0f,1.0f). Internal: ImHash functions tweaks. Added InputText() to query status section.

Renamed ColorEdit/ColorPicker's ImGuiColorEditFlags_RGB/_HSV/_HEX flags to respectively ImGuiColorEditFlags_DisplayRGB/_DisplayHSV/_DisplayHex. This is anticipation of adding new flags to ColorEdit/ColorPicker functions which would make those ambiguous. (#2384) [@haldean]

Fixes warning caused by a missing switch/case. (#2382, #2381)

Log/Capture: Fixed extraneous leading carriage return. Fixed an issue when empty string on a new line would not emit a carriage return.

Log/Capture: Fixed LogXXX functions 'auto_open_depth' parameter being treated as an absolute tree depth instead of a relative one. Fixed CollapsingHeader trailing ascii representation being "#" instead of "##". Minor tidying up the of code.

Internal: Log/Capture: Rework to add an internal LogToBuffer() function which is useful for writing automated tests. Clarified logging state by adding an enum.

Nav: Fixed a tap on AltGR (e.g. German keyboard) from navigation to the menu layer. (follow and extend on e.g #369, #370)

Internal: InputText: Renamed is_editable to !is_readonly, Hopefully more explicit. Renamed internal member. Shuffled some code. Added comments, assert (_will_ trigger on !readonly > readonly edge, old bug).

Version 1.69 WIP

Internal: Changed Scrollbar() signature. Using GetScrollbarID() in InputTextMultiline(). ...

Removed multiple semi-colons (#2368)

Version 1.68

Selectable: Tweaks for #2347 (demo, changelog, member position)

Selectable: add support for specifying text alignment on selectables (#2347) ...

Adds a style variable to Selectable that allows clients to specify the
text alignment within Selectables, adds a section in the demo to
demonstrate selectable text alignment, and a pair of sliders in the
style editor to change selectable alignment on the fly.

In terms of implementation, this one is extremely simple: Selectable was
already calling an API that supports text alignment, but had hard-coded
it to top-left. This changes that to just pass the style variable
straight through to RenderTextClipped. Backwards-compatibility is
preserved by defaulting the text_align parameter to (0, 0), i.e.,
top-left.

This also fixes a bug with selectable text rendering that caused
right-aligned text in a selectable to be clipped incorrectly, because
the wrong clipping rectangle was being used.

Made it illegal/assert when io.DisplayTime == 0.0f (with an exception for the first frame). ...

Causing too many subtle side-effect, e.g. IsNavInputPressed() would return true multiple times in a row.

Demo: Added Auto-Scroll option in Log/Console. Comments. Removed some ImColor() uses.

Font: Moved functions to internal block (not enforced). Made ConfigData pointer const. Added link to stb's notes.

Font: Fixed high-level ImGui::CalcTextSize() used by most widgets from erroneously subtracting 1.0f*scale to calculated text width. Among noticeable side-effects, it would make sequences of repeated Text/SameLine calls not align the same as a single call, and create mismatch between high-level size calculation and those performed with the lower-level ImDrawList api. (#792)

ImDrawData: Added FramebufferScale field (currently a copy of the value from io.DisplayFramebufferScale). ...

This is to allow render functions being written without pulling any data from ImGuiIO, allowing incoming multi-viewport feature to behave on Retina display and with multiple displays. If you are not using a custom binding, please update your render function code ahead of time, and use draw_data->FramebufferScale instead of io.DisplayFramebufferScale. (#2306, #1676)
Examples: Metal, OpenGL2, OpenGL3: Fixed offsetting of clipping rectangle with ImDrawData::DisplayPos != (0,0) when the display frame-buffer scale scale is not (1,1). While this doesn't make a difference when using master branch, this is effectively fixing support for multi-viewport with Mac Retina Displays on those examples. (#2306) Also using ImDrawData::FramebufferScale instead of io.DisplayFramebufferScale.
Examples: Clarified the use the ImDrawData::DisplayPos to offset clipping rectangles.

Window: Fixed initial width of collapsed windows not taking account of contents width (broken in 1.67). (#2336, #176)

Minor tweaks to reduce false positive of PVS Studio static analyzer.

Menus: Tweaked horizontal overlap between parent and child menu (to help convey relative depth) from using style.ItemSpacing.x to style.ItemInnerSpacing.x, the later being expected to be smaller. (#1086)

Added IsItemActivated() as an extension to the IsItemDeactivated/IsItemDeactivatedAfterEdit functions which are useful to implement variety of undo patterns. (#820, #956, #1875)