Index: trunk/src/org/openstreetmap/josm/Main.java
===================================================================
--- trunk/src/org/openstreetmap/josm/Main.java	(revision 11897)
+++ trunk/src/org/openstreetmap/josm/Main.java	(revision 11898)
@@ -517,5 +517,5 @@
 
         // creating toolbar
-        contentPanePrivate.add(toolbar.control, BorderLayout.NORTH);
+        GuiHelper.runInEDTAndWait(() -> contentPanePrivate.add(toolbar.control, BorderLayout.NORTH));
 
         registerActionShortcut(menu.help, Shortcut.registerShortcut("system:help", tr("Help"),
@@ -575,9 +575,9 @@
         FeatureAdapter.registerLoggingAdapter(name -> Logging.getLogger());
 
-        new InitializationTask(tr("Updating user interface"), () -> {
+        new InitializationTask(tr("Updating user interface"), () -> GuiHelper.runInEDTAndWait(() -> {
             toolbar.refreshToolbarControl();
             toolbar.control.updateUI();
             contentPanePrivate.updateUI();
-        }).call();
+        })).call();
     }