Comment 2 for bug 192604

Similar(ish) problem when using the citrix plug-in:

When using an application inside a citrix session (tested just from Windows), if
I right-click in the application's "workpane", two menus come up, the
application's context menu and Mozilla's context menu almost completely
overlayed on top.
The overlay renders the application's context menu essentially mouse-unusable as
you can't see the menu options (though you can scroll over it and make an action
occur using the mouse). The keyboard also allows scrolling over the
application's menu.
The problem (of two menus) does _not_ however occur if a "control area" e.g. a
scrollbar in the application is clicked. In such a case, just the application
context menu shows up.

vsinha