Index: trunk/src/org/openstreetmap/josm/gui/preferences/imagery/ImageryPreference.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/imagery/ImageryPreference.java	(revision 10098)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/imagery/ImageryPreference.java	(revision 10099)
@@ -10,4 +10,5 @@
 import java.awt.FlowLayout;
 import java.awt.Font;
+import java.awt.GraphicsEnvironment;
 import java.awt.GridBagConstraints;
 import java.awt.GridBagLayout;
@@ -160,5 +161,7 @@
         OffsetBookmark.saveBookmarks();
 
-        DownloadDialog.getInstance().refreshTileSources();
+        if (!GraphicsEnvironment.isHeadless()) {
+            DownloadDialog.getInstance().refreshTileSources();
+        }
 
         boolean commonRestartRequired = commonSettings.saveSettings();