Have problems with #Firefox 4 beta dictionary’s? Cant see all installed languages? see http://goo.gl/yrkhf.
- Check installation folder, C:\Program Files (x86)\Mozilla Firefox 4.0 Beta 7\dictionaries
- Copy *.aff and *.dic from another dictionaries folder.
- Restart FF.
Are you planning to create a FF extension.. Then see the next links.. – Lazy Programmers (LP) Guide To Creating A Firefox Mozilla Extension http://goo.gl/l5aZf. A very good guide!!! More see How to create Firefox extensions http://goo.gl/QRAhv
Mozilla has of course lot of useful information http://kb.mozillazine.org/Extension_development