They show up as checkable GButtons in GToolBar, and with (or without) check
marks in menus.
There are a bunch of places to make use of this. This patch only takes
advantage of it in the FileManager for the view type actions.
This makes it possible for e.g GTextEditor to create a bunch of actions
with popular shortcuts like Ctrl+C, etc, without polluting the global
shortcut namespace. Widget-local actions will only activate while their
corresponding widget has focus. :^)
The enabled state of a GAction now propagates both to any toolbar buttons
and any menu items linked to the action. Toolbar buttons are painted in
a grayed out style when disabled. Menu items are gray when disabled. :^)
This patch adds a GShortcut class. Each GAction can have a GShortcut which
will cause the event loop to listen for that key combination app-globally
and activate the event in case it's pressed.
The shortcut will also be displayed when the action is added to a menu.
Use this to hook up Alt+Up with the "open parent directory" action in the
FileManager app. :^)
