Index: trunk/src/org/openstreetmap/josm/gui/MainPanel.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/MainPanel.java	(revision 11549)
+++ trunk/src/org/openstreetmap/josm/gui/MainPanel.java	(revision 11551)
@@ -44,5 +44,5 @@
      * @param showMap If the map should be displayed.
      */
-    protected void updateContent(boolean showMap) {
+    protected synchronized void updateContent(boolean showMap) {
         GuiHelper.assertCallFromEdt();
         MapFrame old = map;
@@ -109,5 +109,5 @@
      * @return {@code true} if the listeners collection changed as a result of the call.
      */
-    public boolean addAndFireMapFrameListener(MapFrameListener listener) {
+    public synchronized boolean addAndFireMapFrameListener(MapFrameListener listener) {
         boolean changed = addMapFrameListener(listener);
         if (changed && map != null) {
@@ -139,5 +139,5 @@
      * @return The panel.
      */
-    public GettingStarted getGettingStarted() {
+    public synchronized GettingStarted getGettingStarted() {
         if (gettingStarted == null) {
             gettingStarted = new GettingStarted();