add calculating methods to bind

[Tom Eugelink]

I came up with this:

startXProperty().bind( *snap(*heightProperty().multiply(0.2)) )


And then:

     private DoubleBinding snap(final ObservableNumberValue other, final Observable... dependencies) {
         return new DoubleBinding() {
             {
                 super.bind(dependencies);
             }

             @Override
             public void dispose() {
                 super.unbind(dependencies);
             }

             @Override
             protected double computeValue() {
                 return NodeUtil.snap(other.doubleValue());
             }

             @Override
             public ObservableList<?> getDependencies() {
                 return new ImmutableObservableList<Observable>(dependencies);
             }
         };
     }

But that always returns 0... I feel this should have worked.

Tom