Toggle Allout Widgets mode.
With a prefix argument ARG, enable Allout Widgets mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
the mode if ARG is omitted or nil.
Allout Widgets mode is an extension of Allout mode that provides
graphical decoration of outline structure. It is meant to
operate along with `allout-mode', via `allout-mode-hook'.
The graphics include:
- guide lines connecting item bullet-icons with those of their subitems.
- icons for item bullets, varying to indicate whether or not the item
has subitems, and if so, whether or not the item is expanded.
- cue area between the bullet-icon and the start of the body headline,
for item numbering, encryption indicator, and distinctive bullets.
The bullet-icon and guide line graphics provide keybindings and mouse
bindings for easy outline navigation and exposure control, extending
outline hot-spot navigation (see `allout-mode').
(fn &optional ARG)