Is it possible to determine if the state of the right mouse button when another app is dragging the cursor over my app?

I’m able to do this fine if my app is doing the dragging (I check the DragGestureEvent that initiates the drag). But I need to know if another app is right-button-dragging.

I’ve tried adding a MouseMotionListener to my JFrame but am not seeing any events when the other app drags over. I’ve got a DropTargetListener on a number of controls, and these are definitely seeing events, but I don’t see a way of detecting the state of the mouse button in any of the handlers.