Keeping tree rows selected during a pop-up menu

[Matt Bragano <maestro485 comcast net>]

I have a TreeView that allows multiple selections.  When multiple 
selections are made and the user right-clicks, a pop-up menu appears 
where the user can choose to add the selected files to a play list.  My 
problem is that whenever the right mouse button is released and the menu 
appears the selections are unselected, which makes the option to add 
selected files useless from the pop-up menu  (although it still works 
fine from the standard menu bar).

So I'm wondering how I can maintain the selection after the TreeView 
itself loses focus to the pop-up menu.  I messed around with 
TreeSelection::set_select_function() but I was unable to make the 
callback slot behave properly. 

Any suggestions?

Thanks,
Matt Bragano