While searching the forums for a solution to this problem, I found this post:
[url]Draw order and GUI elements]
Wherein the very knowledgeable drwr informs the poster that he must place his mouse cursor card in the “gui-popup” bin rather than the “fixed” bin. I tried it, and now my mouse cursor card is on top of the menus, just like I wanted. I agree with the person who mentioned, in that post, that it might be a good idea to add a mention of the “gui-popup” bin to the manual page http://www.panda3d.org/manual/index.php/How_to_Control_Render_Order to make it easier for people to learn of its existence.