google analytics not working with jsdomenu

When opening a web site with Google Analytics Site Overlay, no overlay is loaded.
I realized that the javascript breaks in firefox with the message "opera.version is not a function".

One can rename the variable opera to jsopera (or whatever is unused) at the variable declaration and in all tests with opera or !opera.

This is because jsdomenu.js defines the variable opera as false if it is not under opera, otherwise it is set to true. However, opera seems to provide some information about itself in this object. Google compares the opera object with "undefined" - but false is of course not "undefined".
I guess its better not to use that name as variable, as it would probably break when running under Opera.