Index: trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/ExpressionFactory.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/ExpressionFactory.java	(revision 12513)
+++ trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/ExpressionFactory.java	(revision 12514)
@@ -1034,4 +1034,16 @@
             return !inside(env, codes);
         }
+
+        /**
+         * Determines if the object centroid lies at given lat/lon coordinates.
+         * @param env the environment
+         * @param lat latitude
+         * @param lon longitude
+         * @return {@code true} if the object centroid lies at given lat/lon coordinates
+         * @since 12514
+         */
+        public static boolean at(Environment env, double lat, double lon) { // NO_UCD (unused code)
+            return new LatLon(lat, lon).equalsEpsilon(center(env));
+        }
     }
 
@@ -1308,7 +1320,12 @@
             StringBuilder b = new StringBuilder("ParameterFunction~");
             b.append(m.getName()).append('(');
-            for (int i = 0; i < args.size(); ++i) {
+            for (int i = 0; i < expectedParameterTypes.length; ++i) {
                 if (i > 0) b.append(',');
-                b.append(expectedParameterTypes[i]).append(' ').append(args.get(i));
+                b.append(expectedParameterTypes[i]);
+                if (!needsEnvironment) {
+                    b.append(' ').append(args.get(i));
+                } else if (i > 0) {
+                    b.append(' ').append(args.get(i-1));
+                }
             }
             b.append(')');