Index: src/org/openstreetmap/josm/gui/dialogs/properties/PropertiesDialog.java
===================================================================
--- src/org/openstreetmap/josm/gui/dialogs/properties/PropertiesDialog.java	(revision 5267)
+++ src/org/openstreetmap/josm/gui/dialogs/properties/PropertiesDialog.java	(working copy)
@@ -156,6 +156,8 @@
                 int row = propertyTable.rowAtPoint(e.getPoint());
                 if (row > -1) {
                     propertyEdit(row);
+                } else {
+                    add();
                 }
             } else if (e.getSource() == membershipTable) {
                 int row = membershipTable.rowAtPoint(e.getPoint());
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