Rated 5 out of 5 stars

If you use 7zip to edit the install.rdf file within the xpi and change to 3.0, it installs and works perfectly fine.

Here's the modified file that I used to install it (download and open with Firefox):

http://rapidshare.com/files/123542588/cutemenus_-_crystal_svg-1.9.2-fx_tb_sb_sm.xpi.html

This review is for a previous version of the add-on (1.9.2).