QueryBuilder fires WFS DescribeFeatureType twice per Layer

[justb4]

Using the QueryBuilder like in example http://gxp.opengeo.org/master/examples/query.html users noticed that DescribeFT is always called twice: one time for the layer change and then each time that the attributes combo for the filter comparisons is first selected. It should be only done once as the FT info (in a Store) is already available. See also the image to give an idea what is happening. This is recorded on first pageload and then selecting the attributes combo.