I'm currently using DnD to drag items from a JTable and place them in another container. What I'd like to be able to do is now DnD between different JTables that are placed on different tabs of a JTabbedPane. Unfortunately when I try to drag from one table on tab #1 to another table on tab #2 I'm unable to select tab #2 while I'm dragging. I figure there's got to be an easy way to implement this but can't fine anything.
Sorry, this is going to be zero help to solving your problem, however, I have to say that the feature you are attempting to implement seems like horrible UXP. I realize you may have no control over that but if you do, I'd recommend not dragging items from tab to tab. Visually, it makes no sense. Ok, move along. Nothing to see here.
I don't have tabs as such, but on the left side I have a list of available pages and on the right side I have a panel which displays the current page only. So when I drag from the current page, I hover over the list entry on the left side and that does something to cause it to become the current page. Then I can continue to drag to what's now the current page and drop there.
I can't give you details because my code isn't here, but it wasn't difficult to cause a "hover" event to affect the component underneath it.