Index: trunk/src/org/openstreetmap/josm/gui/mappaint/MapPaintStyles.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/mappaint/MapPaintStyles.java	(revision 7255)
+++ trunk/src/org/openstreetmap/josm/gui/mappaint/MapPaintStyles.java	(revision 7256)
@@ -311,6 +311,8 @@
                     fireMapPaintSylesUpdated();
                     styles.clearCached();
-                    Main.map.mapView.preferenceChanged(null);
-                    Main.map.mapView.repaint();
+                    if (Main.isDisplayingMapView()) {
+                        Main.map.mapView.preferenceChanged(null);
+                        Main.map.mapView.repaint();
+                    }
                 }
             });