Fix various little problems, add track_actor functionality, add extended

plugin info allowing plugins to replace built-in componenets, allow them
to delay their load.

lib/Plugin.vala

@@ -17,11 +17,179 @@
 
 namespace Gala
 {
-	public interface Plugin : Object
+	public enum PluginFunction
 	{
-		public abstract X.Xrectangle[] region { get; protected set; }
+		ADDITION,
+		WINDOW_SWITCHER,
+		DESKTOP,
+		WORKSPACE_VIEW,
+		WINDOW_OVERVIEW
+	}
+
+	public struct PluginInfo
+	{
+		string name;
+		string author;
+
+		/**
+		 * Type of your plugin class, has to be derived from the Plugin class.
+		 */
+		Type plugin_type;
+
+		/**
+		 * This property allows you to override default functionality of gala
+		 * so systems won't be instantiated next to each other. Use
+		 * PluginFunction.ADDITION if no special component is overridden.
+		 */
+		PluginFunction provides;
+
+		/**
+		 * Indicate that your plugin does not need to be started immediately on
+		 * gala's launch but can wait until there's a bit less stuff going on.
+		 * Especially use this if you're adding a completely new ui component.
+		 */
+		bool load_can_wait;
+
+		/**
+		 * You don't have to fill this field, it will be filled by gala with
+		 * the filename in which your module was found.
+		 */
+		string module_name;
+	}
+
+	/**
+	 * This class has to be implemented by every plugin.
+	 * Additionally, the plugin module is required to have a register_plugin
+	 * function which returns a PluginInfo struct.
+	 * The plugin_type field has to be the type of your plugin class derived
+	 * from this class.
+	 */
+	public abstract class Plugin : Object
+	{
+		/**
+		 * The region indicates an area where mouse events should be sent to
+		 * the stage, which means your actors, instead of the windows.
+		 *
+		 * It is calculated by the system whenever update_region is called.
+		 * You can influce it with the custom_region and the track_actor function.
+		 */
+		public X.Xrectangle[] region { get; set; }
+
+		/**
+		 * This list will be merged with the region property. See region for
+		 * more details. Changing this property will cause update_region to be
+		 * called. Default to null.
+		 */
+		protected X.Xrectangle[]? custom_region {
+			get {
+			   return _custom_region;
+			}
+			protected set {
+				_custom_region = value;
+				update_region ();
+			}
+		}
+
+		/**
+		 * Set this property to true while animating an actor if you have tracked
+		 * actors to prevent constant recalculations of the regions during an
+		 * animation.
+		 */
+		protected bool freeze_track { get; protected set; default = false; }
+
+		private X.Xrectangle[]? _custom_region = null;
+		private Gee.LinkedList<Clutter.Actor> tracked_actors = new Gee.LinkedList<Clutter.Actor> ();
+
+		/**
+		 * Emitted when update_region is called. Mainly for internal purposes.
+		 */
+		public signal void region_changed ();
+
+		/**
+		 * Once this method is called you can start adding actors to the stage
+		 * using via the windowmanager instance that is given to you.
+		 *
+		 * @param wm The window manager.
+		 */
 		public abstract void initialize (WindowManager wm);
+
+		/**
+		 * This method is currently not called in the code, however you should
+		 * still implement it to be compatible whenever we decide to use it.
+		 * It should make sure that everything your plugin added to the stage 
+		 * is cleaned up.
+		 */
 		public abstract void destroy ();
+
+		/**
+		 * Listen to changes to the allocation of actor and update the region
+		 * accordingly. You may add multiple actors, their shapes will be 
+		 * combined when one of them changes.
+		 *
+		 * @param actor The actor to be tracked
+		 */
+		public void track_actor (Clutter.Actor actor)
+		{
+			tracked_actors.add (actor);
+			actor.allocation_changed.connect (actor_allocation_changed);
+
+			update_region ();
+		}
+
+		/**
+		 * Stop listening to allocation changes and remove the actor's
+		 * allocation from the region array.
+		 */
+		public void untrack_actor (Clutter.Actor actor)
+		{
+			if (tracked_actors.remove (actor)) {
+				actor.allocation_changed.disconnect (actor_allocation_changed);
+			}
+		}
+
+		/**
+		 * You can call this method to force the system to update the region that
+		 * is used by the window manager. It will automatically upon changes to
+		 * the custom_region property and when a tracked actor's allocation changes
+		 * unless freeze_track is set to true. You may need to call this function
+		 * after setting freeze_track back to false after an animation to make the
+		 * wm aware of the new position of the actor in question.
+		 */
+		public void update_region ()
+		{
+			var has_custom = custom_region != null;
+			var len = tracked_actors.size + (has_custom ? custom_region.length : 0);
+
+			X.Xrectangle[] regions = new X.Xrectangle[len];
+			var i = 0;
+
+			if (has_custom) {
+				for (var j = 0; j < custom_region.length; j++) {
+					regions[i++] = custom_region[j];
+				}
+			}
+
+			foreach (var actor in tracked_actors) {
+				float x, y, w, h;
+				actor.get_transformed_position (out x, out y);
+				actor.get_transformed_size (out w, out h);
+
+				if (w == 0 || h == 0)
+					continue;
+
+				regions[i++] = { (short)x, (short)y, (short)w, (short)h };
+			}
+
+			region = regions;
+
+			region_changed ();
+		}
+
+		private void actor_allocation_changed (Clutter.ActorBox box, Clutter.AllocationFlags f)
+		{
+			if (!freeze_track)
+				update_region ();
+		}
 	}
 }
 

lib/WindowManager.vala

@@ -47,6 +47,7 @@ namespace Gala
 		public abstract void perform_action (ActionType type);
 		public abstract void update_input_area ();
 		public abstract void move_window (Meta.Window? window, Meta.MotionDirection direction);
+		public abstract void switch_to_next_workspace (Meta.MotionDirection direction);
 	}
 }
 

plugins/template/Main.vala

@@ -1,5 +1,5 @@
 //  
-//  Copyright (C) 2012 Tom Beckmann
+//  Copyright (C) 2014 Tom Beckmann
 // 
 //  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
@@ -15,6 +15,13 @@
 //  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 // 
 
+// note on compilation: If you want your own plugin within this source tree
+// don't forget to add the new subdirectory to the plugins' Makefile.am
+// SUBDIRS list and add your Makefile to the list of Makefiles found at
+// about the end of the configure.ac file AC_CONFIG_FILES.
+// The API is currently internal until the API is finalized, so you have
+// to build it in this source tree.
+
 /*
   This is a template class showing some of the things that can be done
   with a gala plugin and how to do them.
@@ -22,10 +29,8 @@
 
 namespace Gala.Plugins.Template
 {
-	public class Main : Object, Gala.Plugin
+	public class Main : Gala.Plugin
 	{
-		public X.Xrectangle[] region { get; protected set; default = {}; }
-
 		Gala.WindowManager? wm = null;
 		const int PADDING = 50;
 
@@ -33,7 +38,7 @@ namespace Gala.Plugins.Template
 
 		// This function is called as soon as Gala has started and gives you
 		// an instance of the GalaWindowManager class.
-		public void initialize (Gala.WindowManager wm)
+		public override void initialize (Gala.WindowManager wm)
 		{
 			// we will save the instance to our wm property so we can use it later again
 			// especially helpful when you have larger plugins with more functions,
@@ -58,18 +63,16 @@ namespace Gala.Plugins.Template
 			red_box.y = rect.y + rect.height - red_box.height - PADDING;
 
 			// to order Gala to deliver mouse events to our box instead of the underlying
-			// windows, we need to mark the region where the quad is located. We do so
+			// windows, we need to mark the region where the quad is located.
-			// by setting the region property. If you have multiple areas, you can just
+			// The plugin class offers an utility function for this purpose, the track_actor
-			// put more rectangle in this array.
+			// function. It will update the region with the allocation of the actor
-			// Gala will listen to updates on this property and update all the areas
+			// whenever its allocation changes. Make sure to set freeze_track to 
-			// any time this changes for any plugin, so don't change this excessively like
+			// true while animating the actor to not make gala update the region
-			// for example if you play an animation, only set the area on the destination
+			// every single frame.
-			// point of the animation instead of making it follow the animated element.
+			// You can also handle the region manually by setting the custom_region
-			X.Xrectangle red_box_area = {
+			// property. The tracked actors and custom regions will be merged by
-				(short)red_box.x, (short)red_box.y,
+			// the plugin.
-				(short)red_box.width, (short)red_box.height
+			track_actor (red_box);
-			};
-			region = { red_box_area };
 
 			// now we'll add our box into the ui_group. This is where all the shell
 			// elements and also the windows and backgrouds are located.
@@ -86,7 +89,7 @@ namespace Gala.Plugins.Template
 		// still it might be a good idea to implement it anyway to make sure
 		// your plugin is compatible in case we'd add disabling specific plugins
 		// in the future
-		public void destroy ()
+		public override void destroy ()
 		{
 			// here you would destroy actors you added to the stage or remove
 			// keybindings
@@ -97,11 +100,27 @@ namespace Gala.Plugins.Template
 }
 
 // this little function just tells Gala which class of those you may have in
-// your plugin is the one you want to start with. Make sure it's public and
+// your plugin is the one you want to start with and delivers some additional
-// returning the type of the right class
+// details about your plugin. It also gives you the option to choose a specific
-public Type register_plugin ()
+// function which your plugin fulfils. Gala will then make sure that there is
+// no duplicate functionality.
+public Gala.PluginInfo register_plugin ()
 {
-	return typeof (Gala.Plugins.Template.Main);
+	return {
+		"template-plugin",                    // the plugin's name
+		"Tom Beckmann <tomjonabc@gmail.com>", // you, the author
+		typeof (Gala.Plugins.Template.Main),  // the type of your plugin class
+
+		Gala.PluginFunction.ADDITION,         // the function which your plugin
+		                                      // fulfils, ADDITION means nothing 
+		                                      // specific
+
+		false                                 // indicates whether your plugin's
+		                                      // start can be delayed until gala
+		                                      // has loaded the important stuff or
+		                                      // if you want your plugin to start
+		                                      // right away. False means wait.
+	};
 }
 
 /*

plugins/template/Makefile.am

@@ -0,0 +1,58 @@
+include $(top_srcdir)/Makefile.common
+
+VAPIDIR = $(top_srcdir)/vapi
+
+BUILT_SOURCES = libgala_template_la_vala.stamp
+
+libgala_template_la_LTLIBRARIES = libgala-template.la
+
+libgala_template_ladir = $(pkglibdir)/plugins
+
+libgala_template_la_LDFLAGS = \
+	$(PLUGIN_LDFLAGS) \
+	$(GALA_CORE_LDFLAGS) \
+	$(top_builddir)/lib/libgala.la \
+	$(NULL)
+
+libgala_template_la_CFLAGS = \
+	$(GALA_CORE_CFLAGS) \
+	-include config.h \
+	-w \
+	-I$(top_builddir)/lib \
+	$(NULL)
+
+libgala_template_la_VALAFLAGS = \
+	$(GALA_CORE_VALAFLAGS) \
+	$(top_builddir)/lib/gala.vapi \
+	--vapidir $(VAPIDIR) \
+	$(VAPIDIR)/config.vapi \
+	$(NULL)
+
+libgala_template_la_LIBADD = \
+	$(GALA_CORE_LIBS) \
+	$(NULL)
+
+libgala_template_la_VALASOURCES = \
+	Main.vala \
+	$(NULL)
+
+nodist_libgala_template_la_SOURCES = \
+	$(BUILT_SOURCES) \
+	$(libgala_template_la_VALASOURCES:.vala=.c) \
+	$(NULL)
+
+libgala_template_la_vala.stamp: $(libgala_template_la_VALASOURCES)
+	$(AM_V_VALA)$(VALAC) \
+		$(libgala_template_la_VALAFLAGS) \
+		-C \
+		$(filter %.vala %.c,$^)
+	$(AM_V_at)touch $@
+
+CLEANFILES = \
+	$(nodist_libgala_template_la_SOURCES) \
+	$(NULL)
+
+EXTRA_DIST = \
+	$(libgala_template_la_VALASOURCES) \
+	$(NULL)
+

plugins/zoom/Main.vala

@@ -17,16 +17,15 @@
 
 namespace Gala.Plugins.Zoom
 {
-	public class Main : Object, Gala.Plugin
+	public class Main : Gala.Plugin
 	{
-		public X.Xrectangle[] region { get; protected set; default = {}; }
 		Gala.WindowManager? wm = null;
 
 		const uint MOUSE_POLL_TIME = 50;
 		uint mouse_poll_timer = 0;
 		float current_zoom = 1.0f;
 
-		public void initialize (Gala.WindowManager wm)
+		public override void initialize (Gala.WindowManager wm)
 		{
 			this.wm = wm;
 			var display = wm.get_screen ().get_display ();
@@ -36,7 +35,7 @@ namespace Gala.Plugins.Zoom
 			display.add_keybinding ("zoom-out", schema, 0, zoom_out);
 		}
 
-		public void destroy ()
+		public override void destroy ()
 		{
 			if (wm == null)
 				return;
@@ -115,8 +114,14 @@ namespace Gala.Plugins.Zoom
 	}
 }
 
-public Type register_plugin ()
+public Gala.PluginInfo register_plugin ()
 {
-	return typeof (Gala.Plugins.Zoom.Main);
+	return Gala.PluginInfo () {
+		name = "Zoom",
+		author = "Gala Developers",
+		plugin_type = typeof (Gala.Plugins.Zoom.Main),
+		provides = Gala.PluginFunction.ADDITION,
+		load_can_wait = false
+	};
 }
 

src/InternalUtils.vala

@@ -99,6 +99,7 @@ namespace Gala
 			// add plugin's requested areas
 			if (area == InputArea.FULLSCREEN || area == InputArea.HOT_CORNER) {
 				foreach (var rect in PluginManager.get_default ().get_all_regions ()) {
+					print ("%i %i %i %i\n", rect.x, rect.y, rect.width, rect.height);
 					rects += rect;
 				}
 			}

src/PluginManager.vala

@@ -17,7 +17,7 @@
 
 namespace Gala
 {
-	delegate Type RegisterPluginFunction ();
+	delegate PluginInfo RegisterPluginFunction ();
 
 	public class PluginManager : Object
 	{
@@ -28,11 +28,21 @@ namespace Gala
 
 		public bool initialized { get; private set; default = false; }
 
+		public signal void regions_changed ();
+
 		X.Xrectangle[] regions;
 
+		public string? window_switcher_provider { get; private set; default = null; }
+		public string? desktop_provider { get; private set; default = null; }
+		public string? window_overview_provider { get; private set; default = null; }
+		public string? workspace_view_provider { get; private set; default = null; }
+
+		Gee.LinkedList<PluginInfo?> load_later_plugins;
+
 		PluginManager ()
 		{
 			plugins = new HashTable<string,Plugin> (str_hash, str_equal);
+			load_later_plugins = new Gee.LinkedList<PluginInfo?> ();
 
 			if (!Module.supported ()) {
 				warning ("Modules are not supported on this platform");
@@ -44,10 +54,12 @@ namespace Gala
 				return;
 
 			try {
-				var enumerator = plugin_dir.enumerate_children (FileAttribute.STANDARD_NAME, 0);
+				var enumerator = plugin_dir.enumerate_children (FileAttribute.STANDARD_NAME +
+					"," + FileAttribute.STANDARD_CONTENT_TYPE, 0);
 				FileInfo info;
 				while ((info = enumerator.next_file ()) != null) {
-					load_module (info.get_name ());
+					if (info.get_content_type () == "application/x-sharedlib")
+						load_module (info.get_name ());
 				}
 			} catch (Error e) {
 				warning (e.message);
@@ -66,48 +78,102 @@ namespace Gala
 
 		bool load_module (string plugin_name)
 		{
-				var path = Module.build_path (plugin_dir.get_path (), plugin_name);
+			var path = Module.build_path (plugin_dir.get_path (), plugin_name);
-				var module = Module.open (path, ModuleFlags.BIND_LOCAL);
+			var module = Module.open (path, ModuleFlags.BIND_LOCAL);
-				if (module == null) {
+			if (module == null) {
-					warning (Module.error ());
+				warning (Module.error ());
-					return false;
+				return false;
-				}
+			}
 
-				void* function;
+			void* function;
-				module.symbol ("register_plugin", out function);
+			module.symbol ("register_plugin", out function);
-				if (function == null) {
+			if (function == null) {
-					warning ("%s failed to register: register_plugin() function not found", plugin_name);
+				warning ("%s failed to register: register_plugin() function not found", plugin_name);
-					return false;
+				return false;
-				}
+			}
-				RegisterPluginFunction register = (RegisterPluginFunction)function;
+			RegisterPluginFunction register = (RegisterPluginFunction)function;
 
-				var type = register ();
+			var info = register ();
-				if (type.is_a (typeof (Plugin)) == false) {
+			if (info.plugin_type.is_a (typeof (Plugin)) == false) {
-					warning ("%s does not return a class of type Plugin", plugin_name);
+				warning ("%s does not return a class of type Plugin", plugin_name);
-					return false;
+				return false;
-				}
+			}
 
-				module.make_resident ();
+			if (!check_provides (info.name, info.provides)) {
+				return false;
+			}
 
-				var plugin = (Plugin)Object.@new (type);
+			info.module_name = plugin_name;
-				plugins.set (plugin_name, plugin);
+			module.make_resident ();
 
-				if (initialized) {
+			if (info.load_can_wait) {
-					initialize_plugin (plugin_name, plugin);
+				load_later_plugins.add (info);
-					get_all_regions (true);
+			} else {
-				}
+				load_plugin_class (info);
+			}
 
-				return true;
+			return true;
 		}
 
-		void initialize_plugin (string name, Plugin plugin)
+		void load_plugin_class (PluginInfo info)
+		{
+			var plugin = (Plugin)Object.@new (info.plugin_type);
+			plugins.set (info.module_name, plugin);
+
+			debug ("Loaded plugin %s (%s)", info.name, info.module_name);
+
+			if (initialized) {
+				initialize_plugin (info.module_name, plugin);
+				get_all_regions (true);
+			}
+		}
+
+		void initialize_plugin (string plugin_name, Plugin plugin)
 		{
 			plugin.initialize (wm);
-			plugin.notify["region"].connect (() => {
+			plugin.region_changed.connect (() => {
 				get_all_regions (true);
+				regions_changed ();
 			});
 		}
 
+		bool check_provides (string name, PluginFunction provides)
+		{
+			var message = "Plugins %s and %s both provide %s functionality, using first one only";
+			switch (provides) {
+				case PluginFunction.WORKSPACE_VIEW:
+					if (workspace_view_provider != null) {
+						warning (message, workspace_view_provider, name, "workspace view");
+						return false;
+					}
+					workspace_view_provider = name;
+					return true;
+				case PluginFunction.WINDOW_OVERVIEW:
+					if (window_overview_provider != null) {
+						warning (message, window_overview_provider, name, "window overview");
+						return false;
+					}
+					window_overview_provider = name;
+					return true;
+				case PluginFunction.DESKTOP:
+					if (desktop_provider != null) {
+						warning (message, desktop_provider, name, "desktop");
+						return false;
+					}
+					desktop_provider = name;
+					return true;
+				case PluginFunction.WINDOW_SWITCHER:
+					if (window_switcher_provider != null) {
+						warning (message, window_switcher_provider, name, "window switcher");
+						return false;
+					}
+					window_switcher_provider = name;
+					return true;
+			}
+
+			return true;
+		}
+
 		public void initialize (WindowManager _wm)
 		{
 			wm = _wm;
@@ -118,6 +184,13 @@ namespace Gala
 			initialized = true;
 		}
 
+		public void load_waiting_plugins ()
+		{
+			foreach (var info in load_later_plugins) {
+				load_plugin_class (info);
+			}
+		}
+
 		public X.Xrectangle[] get_all_regions (bool update = false)
 		{
 			if (update) {

src/Widgets/WorkspaceView.vala

@@ -218,28 +218,6 @@ namespace Gala
 			}
 		}
 		
-		void switch_to_next_workspace (MotionDirection direction)
-		{
-			var display = screen.get_display ();
-			var old_index = screen.get_active_workspace_index ();
-			var neighbor = screen.get_active_workspace ().get_neighbor (direction);
-			
-			neighbor.activate (display.get_current_time ());
-			
-			// if we didnt switch, show a nudge-over animation. need to take the indices 
-			// here since the changing only applies after the animation ends
-			if (old_index == 0 && direction == MotionDirection.LEFT || 
-				old_index == screen.n_workspaces - 1 && direction == MotionDirection.RIGHT) {
-				
-				var dest = (direction == MotionDirection.LEFT ? 32.0f : -32.0f);
-				Compositor.get_window_group_for_screen (screen).animate (Clutter.AnimationMode.LINEAR, 100, x:dest);
-				Clutter.Threads.Timeout.add (210, () => {
-					Compositor.get_window_group_for_screen (screen).animate (Clutter.AnimationMode.LINEAR, 150, x:0.0f);
-					return false;
-				});
-			}
-		}
-		
 		public override void key_focus_out ()
 		{
 			hide ();
@@ -261,7 +239,7 @@ namespace Gala
 					if ((event.modifier_state & Clutter.ModifierType.SHIFT_MASK) != 0)
 						wm.move_window (display.get_focus_window (), MotionDirection.LEFT);
 					else
-						switch_to_next_workspace (MotionDirection.LEFT);
+						wm.switch_to_next_workspace (MotionDirection.LEFT);
 					
 					last_switch_time = current_time;
 					
@@ -270,7 +248,7 @@ namespace Gala
 					if ((event.modifier_state & Clutter.ModifierType.SHIFT_MASK) != 0)
 						wm.move_window (display.get_focus_window (), MotionDirection.RIGHT);
 					else
-						switch_to_next_workspace (MotionDirection.RIGHT);
+						wm.switch_to_next_workspace (MotionDirection.RIGHT);
 					
 					last_switch_time = current_time;
 					
@@ -454,12 +432,5 @@ namespace Gala
 			wins.x = 0.0f;
 			wins.animate (Clutter.AnimationMode.EASE_OUT_EXPO, 500, y : 0.0f);
 		}
-		
-		public void handle_switch_to_workspace (Meta.Display display, Meta.Screen screen, Meta.Window? window,
-			X.Event event, Meta.KeyBinding binding)
-		{
-			var direction = (binding.get_name () == "switch-to-workspace-left" ? MotionDirection.LEFT : MotionDirection.RIGHT);
-			switch_to_next_workspace (direction);
-		}
 	}
 }

src/WindowManager.vala

@@ -21,11 +21,11 @@ namespace Gala
 {
 	public class WindowManagerGala : Meta.Plugin, WindowManager
 	{
-		PluginInfo info;
+		Meta.PluginInfo info;
 		
-		WindowSwitcher winswitcher;
+		WindowSwitcher? winswitcher = null;
-		WorkspaceView workspace_view;
+		WorkspaceView? workspace_view = null;
-		WindowOverview window_overview;
+		WindowOverview? window_overview = null;
 
 		// used to detect which corner was used to trigger an action
 		Clutter.Actor? last_hotcorner;
@@ -47,7 +47,7 @@ namespace Gala
 
 		public WindowManagerGala ()
 		{
-			info = PluginInfo () {name = "Gala", version = Config.VERSION, author = "Gala Developers",
+			info = Meta.PluginInfo () {name = "Gala", version = Config.VERSION, author = "Gala Developers",
 				license = "GPLv3", description = "A nice elementary window manager"};
 			
 			Prefs.set_ignore_request_hide_titlebar (true);
@@ -77,9 +77,12 @@ namespace Gala
 				screensaver = Bus.get_proxy_sync (BusType.SESSION, "org.gnome.ScreenSaver",
 					"/org/gnome/ScreenSaver");
 				screensaver.active_changed.connect (update_input_area);
-			} catch (Error e) { warning (e.message); }
+			} catch (Error e) {
+				screensaver = null;
+				warning (e.message);
+			}
 			
-			var stage = Compositor.get_stage_for_screen (screen) as Clutter.Stage;
+			stage = Compositor.get_stage_for_screen (screen) as Clutter.Stage;
 			
 			var color = BackgroundSettings.get_default ().primary_color;
 			stage.background_color = Clutter.Color.from_string (color);
@@ -114,28 +117,12 @@ namespace Gala
 			window_group.add_child (background_group);
 			window_group.set_child_below_sibling (background_group, null);
 
-			workspace_view = new WorkspaceView (this);
-			workspace_view.visible = false;
-			
-			winswitcher = new WindowSwitcher (this);
-			window_overview = new WindowOverview (this);
-			
-			ui_group.add_child (workspace_view);
-			ui_group.add_child (winswitcher);
-			ui_group.add_child (window_overview);
-
 			var top_window_group = Compositor.get_top_window_group_for_screen (screen);
 			stage.remove_child (top_window_group);
 			ui_group.add_child (top_window_group);
 			
 			/*keybindings*/
 			
-			screen.get_display ().add_keybinding ("expose-windows", KeybindingSettings.get_default ().schema, 0, () => {
-				window_overview.open (true);
-			});
-			screen.get_display ().add_keybinding ("expose-all-windows", KeybindingSettings.get_default ().schema, 0, () => {
-				window_overview.open (true, true);
-			});
 			screen.get_display ().add_keybinding ("switch-to-workspace-first", KeybindingSettings.get_default ().schema, 0, () => {
 				screen.get_workspace_by_index (0).activate (screen.get_display ().get_current_time ());
 			});
@@ -182,19 +169,10 @@ namespace Gala
 				} catch (Error e) { warning (e.message); }
 			});
 			
-			KeyBinding.set_custom_handler ("show-desktop", () => {
-				workspace_view.show (true);
-			});
-			
-			//FIXME we have to investigate this. Apparently alt-tab is now bound to switch-applications
-			// instead of windows, which we should probably handle too
-			KeyBinding.set_custom_handler ("switch-applications", winswitcher.handle_switch_windows);
-			KeyBinding.set_custom_handler ("switch-applications-backward", winswitcher.handle_switch_windows);
-			
 			KeyBinding.set_custom_handler ("switch-to-workspace-up", () => {});
 			KeyBinding.set_custom_handler ("switch-to-workspace-down", () => {});
-			KeyBinding.set_custom_handler ("switch-to-workspace-left", workspace_view.handle_switch_to_workspace);
+			KeyBinding.set_custom_handler ("switch-to-workspace-left", handle_switch_to_workspace);
-			KeyBinding.set_custom_handler ("switch-to-workspace-right", workspace_view.handle_switch_to_workspace);
+			KeyBinding.set_custom_handler ("switch-to-workspace-right", handle_switch_to_workspace);
 			
 			KeyBinding.set_custom_handler ("move-to-workspace-up", () => {});
 			KeyBinding.set_custom_handler ("move-to-workspace-down", () => {});
@@ -214,7 +192,43 @@ namespace Gala
 			
 			BehaviorSettings.get_default ().schema.changed.connect ((key) => update_input_area ());
 
-			PluginManager.get_default ().initialize (this);
+			// initialize plugins and add default components if no plugin overrides them
+			var plugin_manager = PluginManager.get_default ();
+			plugin_manager.initialize (this);
+			plugin_manager.regions_changed.connect (update_input_area);
+
+			if (plugin_manager.workspace_view_provider == null) {
+				workspace_view = new WorkspaceView (this);
+				workspace_view.visible = false;
+				ui_group.add_child (workspace_view);
+				
+				KeyBinding.set_custom_handler ("show-desktop", () => {
+					workspace_view.show (true);
+				});
+			}
+
+			if (plugin_manager.window_switcher_provider == null) {
+				winswitcher = new WindowSwitcher (this);
+				ui_group.add_child (winswitcher);
+
+				//FIXME we have to investigate this. Apparently alt-tab is now bound to switch-applications
+				// instead of windows, which we should probably handle too
+				KeyBinding.set_custom_handler ("switch-applications", winswitcher.handle_switch_windows);
+				KeyBinding.set_custom_handler ("switch-applications-backward", winswitcher.handle_switch_windows);
+			}
+			
+			if (plugin_manager.window_overview_provider == null) {
+				window_overview = new WindowOverview (this);
+				ui_group.add_child (window_overview);
+
+				screen.get_display ().add_keybinding ("expose-windows", KeybindingSettings.get_default ().schema, 0, () => {
+					window_overview.open (true);
+				});
+				screen.get_display ().add_keybinding ("expose-all-windows", KeybindingSettings.get_default ().schema, 0, () => {
+					window_overview.open (true, true);
+				});
+			}
+			
 			update_input_area ();
 
 			stage.show ();
@@ -222,6 +236,11 @@ namespace Gala
 			// let the session manager move to the next phase
 			Meta.register_with_session ();
 
+			Idle.add (() => {
+				plugin_manager.load_waiting_plugins ();
+				return false;
+			});
+			
 			return false;
 		}
 		
@@ -264,14 +283,48 @@ namespace Gala
 			hot_corner.y = y;
 		}
 		
+		void handle_switch_to_workspace (Meta.Display display, Meta.Screen screen, Meta.Window? window,
+			X.Event event, Meta.KeyBinding binding)
+		{
+			var direction = (binding.get_name () == "switch-to-workspace-left" ? MotionDirection.LEFT : MotionDirection.RIGHT);
+			switch_to_next_workspace (direction);
+		}
+		
+		public void switch_to_next_workspace (MotionDirection direction)
+		{
+			var screen = get_screen ();
+			var display = screen.get_display ();
+			var old_index = screen.get_active_workspace_index ();
+			var neighbor = screen.get_active_workspace ().get_neighbor (direction);
+			
+			neighbor.activate (display.get_current_time ());
+			
+			// if we didnt switch, show a nudge-over animation. need to take the indices 
+			// here since the changing only applies after the animation ends
+			if (old_index == 0 && direction == MotionDirection.LEFT || 
+				old_index == screen.n_workspaces - 1 && direction == MotionDirection.RIGHT) {
+				
+				var dest = (direction == MotionDirection.LEFT ? 32.0f : -32.0f);
+				ui_group.animate (Clutter.AnimationMode.LINEAR, 100, x:dest);
+				Timeout.add (210, () => {
+					ui_group.animate (Clutter.AnimationMode.LINEAR, 150, x:0.0f);
+					return false;
+				});
+			}
+		}
+		
 		public void update_input_area ()
 		{
 			var schema = BehaviorSettings.get_default ().schema;
 			var screen = get_screen ();
 			
-			if (screensaver != null && screensaver.get_active ()) {
+			if (screensaver != null) {
-				InternalUtils.set_input_area (screen, InputArea.NONE);
+				try {
-				return;
+					if (screensaver.get_active ()) {
+						InternalUtils.set_input_area (screen, InputArea.NONE);
+						return;
+					}
+				} catch (IOError e) { warning (e.message); }
 			}
 			
 			if (modal_count > 0)
@@ -1018,7 +1071,7 @@ namespace Gala
 			return modal_count > 0;
 		}
 		
-		public override unowned PluginInfo? plugin_info ()
+		public override unowned Meta.PluginInfo? plugin_info ()
 		{
 			return info;
 		}