Restore redraw button icon after fullscreen change

This was previously removed, but it looks like it is still needed for GTK4 to draw button icon at correct size after toggling fullscreen.

clapper_src/buttons.js

@@ -36,6 +36,10 @@ class ClapperCustomButton extends Gtk.Button
         this.margin_end = (isFullscreen) ? 3 : 2;
         this.can_focus = isFullscreen;
 
+        /* Redraw icon after style class change */
+        if(this.icon_name)
+            this.set_icon_name(this.icon_name);
+
         this.isFullscreen = isFullscreen;
     }