Popup on titlebar of JInternalFrame

Hi folks,
I have a rather peculiar need in a JInternalFrame subclass to be able
to react to right-mouse-button clicks on the titlebar (and presses) by
displaying a context menu (JPopupMenu).
I've gone through the typical path to locate the titlebar and can get
my popup to display through a mouselistener; but it immediately
disappears when I release the mouse (I presume the frame's UI delegate is also listening and
turning the event into a drag or window-raise; which makes the popup disappear).
Can anybody suggest a quick and simple way to get at the code in the
UI which listens for mouse events, so I can override it in my subclass
and avoid passing it on if the click was from the right mouse button?