The menu stays at x and y coordinates regardless of where it has been inserted
By default the menu in fixed mode will be positioned at x and y coordinates specified under Menu > Menu Options:
SOLUTION
Add the following code around the SCRIPT tag to flow the menu as other HTML elements of the page:
<div style="position: relative;"> <script language="javascript" src="mymenu.js"></script> </div>The menu will be now relative to the DIV tag and you can place the DIV tag inside a menu cell. At Menu > Menu Options you have to specify menu position 0,0 so the menu will be aligned to the left top corner of the enclosing DIV tag.