Nice add-on Rated 4 out of 5 stars
I'm a Seamonkey user, so I tried your add-on with Seamonkey 2.4.1 (after modification of the install.rdf file).
It seems to work correctly. Please, for the next version, can you make your add-on officially compatible with Seamonkey ?
Please, send me your modified install.rdf file and I will include it in next release. You could send it via email or use gitub...