Stuff

diff --git a/shell/model/homemodel.py b/shell/model/homemodel.py
index 99b0512..a3afdc4 100644
--- a/shell/model/homemodel.py
+++ b/shell/model/homemodel.py
@@ -101,6 +101,7 @@ class HomeModel(gobject.GObject):
             self._remove_activity(window.get_xid())
         if not self._activities:
             self.emit('active-activity-changed', None)
+            self._notify_activity_activation(self._current_activity, None)
 
     def _get_activity_by_xid(self, xid):
         for act in self._activities.values():
@@ -108,10 +109,25 @@ class HomeModel(gobject.GObject):
                 return act
         return None
 
+    def _notify_activity_activation(self, old_activity, new_activity):
+        if old_activity == new_activity:
+            return
+
+        if old_activity:
+            service = old_activity.get_service()
+            if service:
+                service.set_active(False)
+
+        if new_activity:
+            service = new_activity.get_service()
+            if service:
+                service.set_active(True)
+
     def _active_window_changed_cb(self, screen):
         window = screen.get_active_window()
         if window == None:
             self.emit('active-activity-changed', None)
+            self._notify_activity_activation(self._current_activity, None)
             return
         if window.get_window_type() != wnck.WINDOW_NORMAL:
             return
@@ -120,11 +136,14 @@ class HomeModel(gobject.GObject):
         act = self._get_activity_by_xid(window.get_xid())
         if act:
             if act.get_launched() == True:
+                self._notify_activity_activation(self._current_activity, act)
                 self._current_activity = act
             else:
+                self._notify_activity_activation(self._current_activity, None)
                 self._current_activity = None
                 logging.error('Activity for window %d was not yet launched.' % xid)
         else:
+            self._notify_activity_activation(self._current_activity, None)
             self._current_activity = None
             logging.error('Model for window %d does not exist.' % xid)
 
diff --git a/sugar/activity/activity.py b/sugar/activity/activity.py
index b9be5d5..421d7ba 100644
--- a/sugar/activity/activity.py
+++ b/sugar/activity/activity.py
@@ -146,6 +146,10 @@ class Activity(Window, gtk.Container):
         'joined': (gobject.SIGNAL_RUN_FIRST, gobject.TYPE_NONE, ([]))
     }
 
+    __gproperties__ = {
+        'active': (bool, None, None, False, gobject.PARAM_READWRITE)
+    }
+
     def __init__(self, handle, create_jobject=True):
         """Initialise the Activity 
         
@@ -175,6 +179,7 @@ class Activity(Window, gtk.Container):
 
         self.connect('destroy', self._destroy_cb)
 
+        self._active = False
         self._activity_id = handle.activity_id
         self._pservice = presenceservice.get_instance()
         self._shared_activity = None
@@ -213,6 +218,17 @@ class Activity(Window, gtk.Container):
         else:
             self.jobject = None
 
+    def do_set_property(self, pspec, value):
+        if pspec.name == 'active':
+            if self._active != value:
+                self._active = value
+                if not self._active and self.jobject:
+                    self.save()
+
+    def do_get_property(self, pspec):
+        if pspec.name == 'active':
+            return self._active
+
     def _internal_jobject_create_cb(self):
         pass
 
diff --git a/sugar/activity/activityservice.py b/sugar/activity/activityservice.py
index 04629ba..b69ba83 100644
--- a/sugar/activity/activityservice.py
+++ b/sugar/activity/activityservice.py
@@ -15,6 +15,8 @@ # License along with this library; if no
 # Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 # Boston, MA 02111-1307, USA.
 
+import logging
+
 import dbus
 import dbus.service
 
@@ -81,3 +83,7 @@ class ActivityService(dbus.service.Objec
     def execute(self, command, args):
         return self._activity.execute(command, args)
 
+    @dbus.service.method(_ACTIVITY_INTERFACE)
+    def set_active(self, active):
+        logging.debug('ActivityService.set_active: %s.' % active)
+        self._activity.props.active = active