Better handle pushModal failing

Previously we'd leave the focus on the stack, etc.

https://bugzilla.gnome.org/show_bug.cgi?id=595382

js/ui/lookingGlass.js

@@ -542,13 +542,15 @@ LookingGlass.prototype = {
         if (this._open)
             return;
 
+        if (!Main.pushModal(this.actor))
+            return;
+
         this.actor.show();
         this.actor.lower(Main.chrome.actor);
         this._open = true;
 
         Tweener.removeTweens(this.actor);
 
-        Main.pushModal(this.actor);
         global.stage.set_key_focus(this._entry);
 
         Tweener.addTween(this.actor, { time: 0.5,

js/ui/main.js

@@ -205,10 +205,21 @@ function _findModal(actor) {
  * Next, record the current Clutter keyboard focus on a stack.  If the modal stack
  * returns to this actor, reset the focus to the actor which was focused
  * at the time pushModal() was invoked.
+ *
+ * Returns: true iff we successfully acquired a grab or already had one
  */
 function pushModal(actor) {
     let timestamp = global.screen.get_display().get_current_time();
 
+    if (modalCount == 0) {
+        if (!global.begin_modal(timestamp)) {
+            log("pushModal: invocation of begin_modal failed");
+            return false;
+        }
+    }
+
+    global.set_stage_input_mode(Shell.StageInputMode.FULLSCREEN);
+
     modalCount += 1;
     actor.connect('destroy', function() {
         let index = _findModal(actor);
@@ -225,14 +236,7 @@ function pushModal(actor) {
     }
     modalActorFocusStack.push([actor, curFocus]);
 
-    if (modalCount > 1)
-        return;
-
-    if (!global.begin_modal(timestamp)) {
-        log("pushModal: invocation of begin_modal failed");
-        return;
-    }
-    global.set_stage_input_mode(Shell.StageInputMode.FULLSCREEN);
+    return true;
 }
 
 /**

js/ui/overview.js

@@ -277,7 +277,8 @@ Overview.prototype = {
     show : function() {
         if (this.visible)
             return;
-        Main.pushModal(this._dash.actor);
+        if (!Main.pushModal(this._dash.actor))
+            return;
 
         this.visible = true;
         this.animationInProgress = true;

js/ui/runDialog.js

@@ -186,10 +186,12 @@ RunDialog.prototype = {
         if (this._isOpen) // Already shown
             return;
 
+        if (!Main.pushModal(this._group))
+            return;
+
         this._isOpen = true;
         this._group.show();
 
-        Main.pushModal(this._group);
         global.stage.set_key_focus(this._entry);
     },