Don't crash when you happen to select a window with alt-tab that has just

disappeared. (forward port)

svn path=/trunk/kdebase/kwin/; revision=121076

tabbox.cpp

@@ -161,6 +161,8 @@ Client* TabBox::currentClient()
 {
     if ( mode() != WindowsMode )
 	return 0;
+    if (!workspace()->hasClient( client ))
+        return 0;
     return client;
 }
 

workspace.cpp

@@ -736,6 +736,7 @@ bool Workspace::destroyClient( Client* c)
         return FALSE;
 
     storeFakeSessionInfo( c );
+
     if (clients.contains(c))
 	removeClient(c);
 
@@ -752,6 +753,10 @@ bool Workspace::destroyClient( Client* c)
     if ( c == last_active_client )
         last_active_client = 0;
     delete c;
+
+    if (tab_grab)
+       tab_box->repaint();
+
     updateClientArea();
     return TRUE;
 }