Index: /src/org/openstreetmap/josm/gui/dialogs/PropertiesDialog.java
===================================================================
--- /src/org/openstreetmap/josm/gui/dialogs/PropertiesDialog.java	(revision 251)
+++ /src/org/openstreetmap/josm/gui/dialogs/PropertiesDialog.java	(revision 252)
@@ -210,5 +210,7 @@
 				if (allData.containsKey(key)) {
 					Vector<String> newValues = new Vector<String>(allData.get(key));
+					Object oldValue = values.getSelectedItem();
 					values.setModel(new DefaultComboBoxModel(newValues));
+					values.setSelectedItem(oldValue);
 					values.getEditor().selectAll();
 				}