When creating shortcuts, there almost always are a trigger and an action
available for use. So make gtk_shortcut_new() take those as arguments.
Also add gtk_shortcut_new_with_arguments() so people can easily pass
those in, too.
Similar to GtkShortcutTrigger, GtkShortCutAction provides all the
different ways to activate a shortcut.
So far, these different ways are supported:
- do nothing
- Call a user-provided callback
- Call gtk_widget_activate()
- Call gtk_widget_mnemonic_activate()
- Emit an action signal
- Activate an action from the widget's action muxer
It's an outdated technology now that everybody is using GActionGroups.
If somebody wanted to support changeable shortcuts, they'd need to
reintroduce it in another way.
This adds an interface for taking care of shortcut controllers with
managed scope.
Only GtkWindow currently implements this interface, so we need to ensure
that we check if any top-level widget we reach is a shortcuts manager
before we call into it.
Mnemonics need to be triggered with help from the controllers (who
determine the modifiers). Support for that has been added, too.
Mnemonics do not use this yet though.
Allow setting the scope for a controller. The scope determines at what
point in event propagation the shortcuts will be activated.
Local scope is the usual activation, global scope means that the root
widget activates the shortcuts - ie they are activated at the very
start of event propagation (for global capture events) or the very end
(for global bubble events).
Managed scope so far is unimplemented.
This is supposed to be used to replace accelerators and mnemonics.
The function lives in gtkaccelgroup.c, so there's no need to have that
call a private function in another source file. Instead, make that
other source file call gtk_accelerator_get_label() instead.
The shortcut controllers are limited to same-native,
so we need to duplicate the Tab and arrow key bindings
for focus handling, as well as the Enter bindings for
activation.
