ListGrid intercept and stop drop from a drag and drop

[gilcollins]

SmartGWT Nightly from 10292010
GWT 2.0.4

I can't seem to find how to intercept a drop from a drag and drop.

I have 3 ListGrid's
1...primary has values from my DataSource (can drag to 2 or 3 but none can drop here)
2...qualifiers has values that can be dropped from 1 (can only receive drop)
3...excludes has values that can be dropped from 1 (can only receive drop)

What I want to do is ...if the record is already in 3 then it can't be dropped to 2.

Is there a way to intercept the drop and stop it from being added to 2 if it exists in 3 already?

Thank you for your help.

UPDATE: I found I can use addRecordDropHandler, from another post.

[Isomorphic]

Yes 'recordDropHandler()' should work for you. Let us know if you run into further issues

[Donatello]

Right.

The way to do this is to cancel the event like this :

this.addRecordDropHandler(new RecordDropHandler() {
    @Override
    public void onRecordDrop(RecordDropEvent event) {
        boolean dontDropThisOne = true;
        if (dontDropThisOne) {
            event.cancel();
        }
    }
});