Multi-Select Tree Control

I'm using the CXTPTreeCtrl class in an application and I have it set to allow multiple selects.  You can also drag/drop tree items.  The problem i'm having is that if you've got multiple items selected that are not contiguous in the tree then you try to click and drag them by clicking on one of the selected items, it will deselect all but the clicked on item and begin the drag. 

If you have more than one item that are contiguous in the tree, and do the same thing, it won't have the problem. 

Update: I recently discovered that there's more to it than that:
If you have the following items in the tree:

node1  < 1st selection
node2
node3  < 2nd selection

then try to drag node1, it works fine.  If you do the same and try to drag node 3, it will deselect node1.  So it looks like if you click on a selected node that doesn't have focus, it will work okay.  Otherwise, it will deselect the others.

If you look at the TreeCtrl sample that's part of the 10.3 installation, you will be able to reproduce the issue.

Does anyone know if there's an easy workaround for this problem?  Is it a problem or is this expected behaviour? 

Thanks,
Karim