diff --git a/abstract_client.h b/abstract_client.h
--- a/abstract_client.h
+++ b/abstract_client.h
@@ -79,6 +79,11 @@
      */
     Q_PROPERTY(bool active READ isActive NOTIFY activeChanged)
 
+    /**
+     * The activities this Client is on. If the Client is on all activities the property is empty.
+     */
+    Q_PROPERTY(QStringList activities READ activities WRITE setOnActivities NOTIFY activitiesChanged)
+
     /**
      * The desktop this Client is on. If the Client is on all desktops the property has value -1.
      * This is a legacy property, use x11DesktopIds instead
@@ -880,6 +885,7 @@
      * Emitted whenever the demands attention state changes.
      */
     void demandsAttentionChanged();
+    void activitiesChanged(KWin::AbstractClient* client);
     void desktopPresenceChanged(KWin::AbstractClient*, int); // to be forwarded by Workspace
     void desktopChanged();
     void x11DesktopIdsChanged();