For example, here's a popup I define for my lsmail display:


It is assigned to lsmail with this line:


so that the left top corner of the menu is aligned with the bottom left corner of the lsmail graphic. You can do the same type of thing with shortcuts. Just make sure that your default popup.rc file - the one with your main right-click-on-the-desktop-menu - is included *before* you go off and define any other popups. (At least, I think that would still break things...)