Check if gnome-screensaver is running before activating hot corners, fix bug #1084288.

CMakeLists.txt

@@ -66,6 +66,7 @@ vala_precompile(VALA_C
     src/Widgets/WindowThumb.vala
     src/Widgets/WorkspaceThumb.vala
     src/Widgets/WorkspaceView.vala
+    src/Services/ScreenSaver.vala
     ${CMAKE_BINARY_DIR}/src/Config.vala
 PACKAGES
     granite

src/Plugin.vala

@@ -43,6 +43,8 @@ namespace Gala
 		WorkspaceView workspace_view;
 		Zooming zooming;
 		WindowOverview window_overview;
+
+		Gala.Services.ScreenSaver screensaver;
 		
 		Window? moving; //place for the window that is being moved over
 		
@@ -192,6 +194,9 @@ namespace Gala
 				stage.add_child (hot_corner);
 				
 				hot_corner.enter_event.connect (() => {
+					if (screensaver_active ())
+						return false;
+
 					perform_action ((ActionType)BehaviorSettings.get_default ().schema.get_enum (key));
 					return false;
 				});
@@ -200,6 +205,21 @@ namespace Gala
 			hot_corner.x = x;
 			hot_corner.y = y;
 		}
+
+		bool screensaver_active ()
+		{
+			if (screensaver == null) {
+				try {
+					screensaver = Bus.get_proxy_sync (BusType.SESSION,
+													  "org.gnome.ScreenSaver",
+													  "/org/gnome/ScreenSaver");
+				} catch (GLib.IOError error) {
+					return false;
+				}
+			}
+
+			return screensaver.GetActive ();
+		}
 		
 		public void update_input_area ()
 		{

src/Services/ScreenSaver.vala

@@ -0,0 +1,29 @@
+//  
+//  Copyright (C) 2012 Jaap Broekhuizen
+// 
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+// 
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU General Public License for more details.
+// 
+//  You should have received a copy of the GNU General Public License
+//  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+// 
+
+using Meta;
+
+namespace Gala.Services
+{
+
+	[DBus (name = "org.gnome.ScreenSaver")]
+	public interface ScreenSaver : GLib.Object
+	{
+		public abstract bool GetActive () throws GLib.IOError;
+	}
+
+}