Implement horizontal scrolling with Shift+Scroll ...

This is standard scrolling behaviour in most applications.

IsWindowHovered() made change which should have no effect in master but fix result of IsWindowHovered(ImGuiHoveredFlags_ChildWindows) over multiple viewport in docking branch. (#2432)

Comments, todo list, remove trailing spaces.

GetMouseDragDelta(): also returns the delta on the mouse button released frame. Verify that mouse positions are valid otherwise returns zero. Removed obsolete comment. Tweaked demo. (#2419)

Version 1.70 WIP

Version 1.69, comments, typos

Internals: Fixed Navigation from reaching ImGuiItemFlags_Disabled items (#211) + Examples comments

Fix typos. (#2413)

Don't use const qualified parameters in declarations. ...

This fixes warnings from clang-tidy like this:

    parameter 'v_max' is const-qualified in the function declaration;
    const-qualification of parameters only has an effect in function definitions

Since values (rather than references or pointers) don't need to be
const, they don't need to be marked that way in the function declaration.

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.