; Merge from origin/emacs-27

The following commits were skipped:

bc10e467f1 Backport: Rectify allout-widgets region undecoration so it...
82742e295d Backport: Resolve missing button-region keymap bindings.
2035ecca57 Backport: Provide missing let definition to prevent backgr...
3071cecda0 Backport: Don't let item decoration be disrupted by too-sh...
044960ead2 Backport: Fix allout-widgets-mode handling of edits to ite...