Index: /src/org/openstreetmap/josm/gui/dialogs/PropertiesDialog.java
===================================================================
--- /src/org/openstreetmap/josm/gui/dialogs/PropertiesDialog.java	(revision 250)
+++ /src/org/openstreetmap/josm/gui/dialogs/PropertiesDialog.java	(revision 251)
@@ -211,4 +211,5 @@
 					Vector<String> newValues = new Vector<String>(allData.get(key));
 					values.setModel(new DefaultComboBoxModel(newValues));
+					values.getEditor().selectAll();
 				}
             }