Themes: Apply change of dark/light theme instantly

Fixes #10441

gajim/gtk/css_config.py

@@ -121,8 +121,7 @@ def prefer_dark(self):
             return settings.get_property('gtk-application-prefer-dark-theme')
         return setting == Theme.DARK
 
-    @staticmethod
-    def set_dark_theme(value=None):
+    def set_dark_theme(self, value=None):
         if value is None:
             value = app.settings.get('dark_theme')
         else:
@@ -134,6 +133,7 @@ def set_dark_theme(value=None):
             settings.reset_property('gtk-application-prefer-dark-theme')
             return
         settings.set_property('gtk-application-prefer-dark-theme', bool(value))
+        self._load_css()
 
     def _load_css(self):
         self._load_css_from_file('gajim.css', CSSPriority.APPLICATION)
@@ -156,14 +156,16 @@ def _load_css_from_file(self, filename, priority):
             return
         self._activate_css(css, priority)
 
-    @staticmethod
-    def _activate_css(css, priority):
+    def _activate_css(self, css, priority):
         try:
             provider = Gtk.CssProvider()
             provider.load_from_data(bytes(css.encode('utf-8')))
             Gtk.StyleContext.add_provider_for_screen(Gdk.Screen.get_default(),
                                                      provider,
                                                      priority)
+            self._load_selected()
+            self._activate_theme()
+
         except Exception:
             log.exception('Error loading application css')
 

gajim/gtk/preferences.py

@@ -719,12 +719,14 @@ def _on_edit_themes(self, *args):
     def _on_theme_changed(value, *args):
         app.css_config.change_theme(value)
         app.nec.push_incoming_event(NetworkEvent('theme-update'))
+        app.nec.push_incoming_event(NetworkEvent('style-changed'))
         app.interface.roster.repaint_themed_widgets()
         app.interface.roster.change_roster_style(None)
 
     @staticmethod
     def _on_dark_theme(value, *args):
         app.css_config.set_dark_theme(int(value))
+        app.nec.push_incoming_event(NetworkEvent('style-changed'))
 
 
 class Emoji(PreferenceBox):