Creates a new <code>TreeDropTargetEffect</code> to handle the drag under effect on the specified <code>Tree</code>.
@param tree the <code>Tree</code> over which the user positions the cursor to drop the data
See Implementation
Creates a new <code>TreeDropTargetEffect</code> to handle the drag under effect on the specified <code>Tree</code>.
@param tree the <code>Tree</code> over which the user positions the cursor to drop the data