Use new plugin-modality functionality in Mutter

We now have functionality in Mutter to grab the keyboard on behalf
of a plugin. This avoids interactions with the key handling code
in Mutter that could leave the user with an inconsistent state
and no way to get out of it.

src/shell-global.[ch]: Change shell_global_grab_keyboard() and
  shell_global_grab_keyboard() to shell_global_begin_modal()
  shell_global_end_modal() and call mutter_plugin_begin_modal()
  mutter_plugin_end_modal() rather than directly grabbing the
  keyboard.
main.js: Call global.begin_modal/end_modal from Main.startModal()
  and Main.endModal()
altTab.js; Remove call to Main.startModal() - we're letting Mutter
  handle modality for Alt-Tab.
main.js lookingGlass.js overview.js runDialog.js: Rename
  Main.startModal() to Main.beginModal() for consistency with
  naming in mutter and ShellGlobal.

http://bugzilla.gnome.org/show_bug.cgi?id=590686

js/ui/altTab.js

@@ -144,8 +144,6 @@ AltTabPopup.prototype = {
     show : function(initialSelection) {
         let global = Shell.Global.get();
 
-        Main.startModal();
-
         global.window_group.add_actor(this._overlay);
         this._overlay.raise_top();
         this._overlay.show();
@@ -164,8 +162,6 @@ AltTabPopup.prototype = {
     destroy : function() {
         this.actor.destroy();
         this._overlay.destroy();
-
-        Main.endModal();
     },
 
     select : function(n) {

js/ui/lookingGlass.js

@@ -555,7 +555,7 @@ LookingGlass.prototype = {
 
         Tweener.removeTweens(this.actor);
 
-        if (!Main.startModal())
+        if (!Main.beginModal())
             return;
 
         let global = Shell.Global.get();

js/ui/main.js

@@ -137,10 +137,11 @@ function _removeUnusedWorkspaces() {
 // Used to go into a mode where all keyboard and mouse input goes to
 // the stage. Returns true if we successfully grabbed the keyboard and
 // went modal, false otherwise
-function startModal() {
+function beginModal() {
     let global = Shell.Global.get();
+    let timestamp = global.screen.get_display().get_current_time();
 
-    if (!global.grab_keyboard())
+    if (!global.begin_modal(timestamp))
         return false;
     global.set_stage_input_mode(Shell.StageInputMode.FULLSCREEN);
 
@@ -151,8 +152,9 @@ function startModal() {
 
 function endModal() {
     let global = Shell.Global.get();
+    let timestamp = global.screen.get_display().get_current_time();
 
-    global.ungrab_keyboard();
+    global.end_modal(timestamp);
     global.set_stage_input_mode(Shell.StageInputMode.NORMAL);
     inModal = false;
 }

js/ui/overview.js

@@ -271,7 +271,7 @@ Overview.prototype = {
     show : function() {
         if (this.visible)
             return;
-        if (!Main.startModal())
+        if (!Main.beginModal())
             return;
 
         this.visible = true;

js/ui/runDialog.js

@@ -124,7 +124,7 @@ RunDialog.prototype = {
         if (this._isOpen) // Already shown
             return;
 
-        if (!Main.startModal())
+        if (!Main.beginModal())
             return;
             
         this._isOpen = true;

src/shell-global.c

@@ -40,7 +40,6 @@ struct _ShellGlobal {
   
   MutterPlugin *plugin;
   ShellWM *wm;
-  gboolean keyboard_grabbed;
   const char *imagedir;
   const char *configdir;
 
@@ -475,66 +474,42 @@ _shell_global_set_plugin (ShellGlobal  *global,
 }
 
 /**
- * shell_global_grab_keyboard:
+ * shell_global_begin_modal:
  * @global: a #ShellGlobal
  *
- * Grab the keyboard to the stage window. The stage will receive
- * all keyboard events until shell_global_ungrab_keyboard() is called.
- * This is appropriate to do when the desktop goes into a special
- * mode where no normal global key shortcuts or application keyboard
- * processing should happen.
+ * Grabs the keyboard and mouse to the stage window. The stage will
+ * receive all keyboard and mouse events until shell_global_end_modal()
+ * is called. This is used to implement "modes" for the shell, such as the
+ * overview mode or the "looking glass" debug overlay, that block
+ * application and normal key shortcuts.
+ *
+ * Returns value: %TRUE if we succesfully entered the mode. %FALSE if we couldn't
+ *  enter the mode. Failure may occur because an application has the pointer
+ *  or keyboard grabbed, because Mutter is in a mode itself like moving a
+ *  window or alt-Tab window selection, or because shell_global_begin_modal()
+ *  was previouly called.
  */
 gboolean
-shell_global_grab_keyboard (ShellGlobal *global)
+shell_global_begin_modal (ShellGlobal *global,
+                          guint32      timestamp)
 {
-  MetaScreen *screen = mutter_plugin_get_screen (global->plugin);
-  MetaDisplay *display = meta_screen_get_display (screen);
-  Display *xdisplay = meta_display_get_xdisplay (display);
   ClutterStage *stage = CLUTTER_STAGE (mutter_plugin_get_stage (global->plugin));
   Window stagewin = clutter_x11_get_stage_window (stage);
 
-  /* FIXME: we need to coordinate with the rest of Metacity or we
-   * may grab the keyboard away from other portions of Metacity
-   * and leave Metacity in a confused state. An X client is allowed
-   * to overgrab itself, though not allowed to grab they keyboard
-   * away from another applications.
-   */
-  if (global->keyboard_grabbed)
-    return FALSE;
-
-  if (XGrabKeyboard (xdisplay, stagewin,
-                     False, /* owner_events - steal events from the rest of metacity */
-                     GrabModeAsync, GrabModeAsync,
-                     CurrentTime) != Success)
-    return FALSE; /* probably AlreadyGrabbed, some other app has a keyboard grab */
-
-  global->keyboard_grabbed = TRUE;
-
-  return TRUE;
+  return mutter_plugin_begin_modal (global->plugin, stagewin, None, 0, timestamp);
 }
 
 /**
- * shell_global_ungrab_keyboard:
+ * shell_global_end_modal:
  * @global: a #ShellGlobal
  *
- * Undoes the effect of shell_global_grab_keyboard
+ * Undoes the effect of shell_global_begin_modal().
  */
 void
-shell_global_ungrab_keyboard (ShellGlobal *global)
+shell_global_end_modal (ShellGlobal *global,
+                        guint32      timestamp)
 {
-  MetaScreen *screen;
-  MetaDisplay *display;
-  Display *xdisplay;
-
-  g_return_if_fail (global->keyboard_grabbed);
-
-  screen = mutter_plugin_get_screen (global->plugin);
-  display = meta_screen_get_display (screen);
-  xdisplay = meta_display_get_xdisplay (display);
-
-  XUngrabKeyboard (xdisplay, CurrentTime);
-
-  global->keyboard_grabbed = FALSE;
+  mutter_plugin_end_modal (global->plugin, timestamp);
 }
 
 /* Code to close all file descriptors before we exec; copied from gspawn.c in GLib.

src/shell-global.h

@@ -64,8 +64,10 @@ GList *shell_global_get_windows (ShellGlobal *global);
 void _shell_global_set_plugin (ShellGlobal  *global,
 			       MutterPlugin *plugin);
 
-gboolean shell_global_grab_keyboard   (ShellGlobal *global);
-void     shell_global_ungrab_keyboard (ShellGlobal *global);
+gboolean shell_global_begin_modal (ShellGlobal *global,
+				   guint32      timestamp);
+void     shell_global_end_modal   (ShellGlobal *global,
+				   guint32      timestamp);
 
 void shell_global_reexec_self (ShellGlobal *global);