When wobble banner is placed directly under a drop down menu, by default the wobble banner is on top and the submenu appears behind it.

To make the drop down menu appear on top, modify the file:

/modules/mod_wobblebanner/mod_wobblebanner.php

Add the following after line 89 (var soWobbleBanner = new SWFObject ........)

soWobbleBanner.addParam("wmode", "opaque");