Right-click on Table row works on iPad, but right-click on Tree does not

I noted that my Vaadin 7 app works relatively well on an iPad, but wonder if whatever it is that makes a right-click on a Table row (triggers a context menu) can be made to work for a Tree element? When I press and hold over a Table row, I get the context menu, but such a press and hold has no effect on a Tree item. It seems these could be handled in a similar way so they both work. Thanks!