Fix panel sometimes being behind windows

Author: leolost2605

src/ShellClients/PanelClone.vala

@@ -77,6 +77,12 @@ public class Gala.PanelClone : Object {
 
     private void update_visible () {
         actor.visible = !panel_hidden;
+
+        if (actor.visible && !wm.get_display ().get_monitor_in_fullscreen (panel.window.get_monitor ())) {
+            // The actor has just been revealed, make sure it's at the top
+            // https://github.com/elementary/gala/issues/2080
+            actor.get_parent ().set_child_above_sibling (actor, null);
+        }
     }
 
     private void update_clone_position () {