I would give IM-Translator a 5 instead of a four except for one very frequent annoyance. One or more times per day it stops working. I have to go into Firefox's Extension Manager and turn IM-Translator off and then back on to get it working again.
This has been a problem for at least a year, and disrupts my workflow (because I have lots of tabs, and have a hard time getting back to where I was from the Extension Manager tab, which is always at the far right of the tab bar).
When this happens, IM-Translator also disappears from the right-click menu. And I have made a donation, so that shouldn't be a reason.
