Index: trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/Multipolygon.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/Multipolygon.java	(revision 4638)
+++ trunk/src/org/openstreetmap/josm/data/osm/visitor/paint/relations/Multipolygon.java	(revision 4639)
@@ -202,5 +202,5 @@
         private PolyData(List<Node> nodes, boolean selected, Collection<Long> wayIds) {
             this.wayIds = Collections.unmodifiableCollection(wayIds);
-            this.nodes = nodes;
+            this.nodes = new ArrayList<Node>(nodes);
             this.selected = selected;
             this.inners = new ArrayList<Multipolygon.PolyData>();