Index: trunk/src/org/openstreetmap/josm/actions/SessionSaveAsAction.java
===================================================================
--- trunk/src/org/openstreetmap/josm/actions/SessionSaveAsAction.java	(revision 9628)
+++ trunk/src/org/openstreetmap/josm/actions/SessionSaveAsAction.java	(revision 9629)
@@ -35,4 +35,6 @@
 import org.openstreetmap.josm.gui.ExtendedDialog;
 import org.openstreetmap.josm.gui.HelpAwareOptionPane;
+import org.openstreetmap.josm.gui.MapFrame;
+import org.openstreetmap.josm.gui.MapFrameListener;
 import org.openstreetmap.josm.gui.layer.Layer;
 import org.openstreetmap.josm.gui.widgets.AbstractFileChooser;
@@ -49,5 +51,5 @@
  * @since 4685
  */
-public class SessionSaveAsAction extends DiskAccessAction {
+public class SessionSaveAsAction extends DiskAccessAction implements MapFrameListener {
 
     private transient List<Layer> layers;
@@ -71,4 +73,5 @@
                 null, toolbar, "save_as-session", installAdapters);
         putValue("help", ht("/Action/SessionSaveAs"));
+        Main.addMapFrameListener(this);
     }
 
@@ -284,3 +287,8 @@
         setEnabled(Main.isDisplayingMapView());
     }
+
+    @Override
+    public void mapFrameInitialized(MapFrame oldFrame, MapFrame newFrame) {
+        updateEnabledState();
+    };
 }