Index: applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/JMapViewer.java
===================================================================
--- applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/JMapViewer.java	(revision 32722)
+++ applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/JMapViewer.java	(revision 32723)
@@ -309,5 +309,5 @@
 
         if (markers && mapMarkerList != null) {
-            synchronized (mapMarkerList) {
+            synchronized (this) {
                 for (MapMarker marker : mapMarkerList) {
                     if (marker.isVisible()) {
@@ -323,5 +323,5 @@
 
         if (rectangles && mapRectangleList != null) {
-            synchronized (mapRectangleList) {
+            synchronized (this) {
                 for (MapRectangle rectangle : mapRectangleList) {
                     if (rectangle.isVisible()) {
@@ -338,5 +338,5 @@
 
         if (polygons && mapPolygonList != null) {
-            synchronized (mapPolygonList) {
+            synchronized (this) {
                 for (MapPolygon polygon : mapPolygonList) {
                     if (polygon.isVisible()) {
@@ -657,5 +657,5 @@
 
         if (mapPolygonsVisible && mapPolygonList != null) {
-            synchronized (mapPolygonList) {
+            synchronized (this) {
                 for (MapPolygon polygon : mapPolygonList) {
                     if (polygon.isVisible())
@@ -666,5 +666,5 @@
 
         if (mapRectanglesVisible && mapRectangleList != null) {
-            synchronized (mapRectangleList) {
+            synchronized (this) {
                 for (MapRectangle rectangle : mapRectangleList) {
                     if (rectangle.isVisible())
@@ -675,5 +675,5 @@
 
         if (mapMarkersVisible && mapMarkerList != null) {
-            synchronized (mapMarkerList) {
+            synchronized (this) {
                 for (MapMarker marker : mapMarkerList) {
                     if (marker.isVisible())