Changing Gtk accelerator set by glade

Question

I'm using Gtk (python3) + Glade to create an application. I've set some accelerators in glade like this :

 <child>
     <object class="GtkImageMenuItem" id="imagemenuitem5">
         <property name="label">gtk-quit</property>
         <accelerator key="q" signal="activate" modifiers="GDK_CONTROL_MASK"/>
     </object>
 </child>

But I don't see how I can change the accelerator for this event to something else while the application is running. Is it possible? Is my implementation wrong for what i plan to do ?

Answer 1

The <accelerator> element uses gtk_widget_add_accelerator() internally. From the documentation of that function:

Accelerators added through this function are not user changeable during runtime. If you want to support accelerators that can be changed by the user, use gtk_accel_map_add_entry() and gtk_widget_set_accel_path() or gtk_menu_item_set_accel_path() instead.

In fact there is even a more modern way to do it than that, using GAction, GApplication, and GMenuModel, without creating any menu bars at all. Here's an example of changing the accelerators of a menu item at runtime:

from gi.repository import Gio, Gtk


class App(Gtk.Application):
    def __init__(self, **props):
        super(App, self).__init__(application_id='org.gnome.example',
            flags=Gio.ApplicationFlags.FLAGS_NONE, **props)
        # Activating the LEP GEX VEN ZEA menu item will rotate through these
        # accelerator keys
        self.keys = ['L', 'G', 'V', 'Z']

    def do_activate(self):
        Gtk.Application.do_activate(self)

        actions = self.create_actions()
        self.add_action(actions['quit'])

        self.win = Gtk.ApplicationWindow()
        self.add_window(self.win)
        self.win.add_action(actions['lep'])
        self.set_accels_for_action('win.lep', ['<primary>' + self.keys[0]])
        # Ctrl-Q is automatically assigned to an app action named quit

        model = self.create_menus()
        self.set_menubar(model)

        actions['lep'].connect('activate', self.on_lep_activate)
        actions['quit'].connect('activate', lambda *args: self.win.destroy())

        self.win.show_all()

    def create_actions(self):
        return {name: Gio.SimpleAction(name=name) for name in ['lep', 'quit']}

    def create_menus(self):
        file_menu = Gio.Menu()
        file_menu.append('LEP GEX VEN ZEA', 'win.lep')
        file_menu.append('Quit', 'app.quit')
        menu = Gio.Menu()
        menu.append_submenu('File', file_menu)
        return menu

    def on_lep_activate(self, *args):
        self.keys = self.keys[1:] + self.keys[:1]
        self.set_accels_for_action('win.lep', ['<primary>' + self.keys[0]])

if __name__ == '__main__':
    App().run([])

You can also do some of this with Glade files and hook it up automatically by creating a menus.ui file and making it available to your app at a particular GResource path: this is described here.