Dear sienori! Thank for your Simple Translate for Firefox! This is а great addon.
Please, implement this:
1/ When you click on the translation button, the text selection should not disappear. This disorientates the user in the text.
2/ Button "Copy translated text".
http://ipic.su/img/img7/fs/ScreenShot_210.1577111397.png

ممتاز
الرجاء اضافة امكانية الاستماع الي النطق

Is it possible to translate when you hover over the button?

O MELHOR tradutor para Firefox que testei até agora...

简单而又强大！

De todos que testei, essa foi definitivamente a melhor opção, sem duvidas, muito dinâmica e leve, quero mais a frente poder doar para contribuir com o projeto. Congratulations developers.

Incrível, tive que criar até uma conta para poder dizer o quanto esse app é fenomenal

Thank you!!

Very useful and really simple. The best solution for context translation for firefox. But, dear developer, can you see "xtranslate" add-on for chromium and make some functions like there? For example, possibility of choose the other translation engine - bing or yandex. Sometimes other services have a better quality of translation and switch between is really good option. Also make better formatting for source text is can be cool. I really hope that extension will be better and better in future.

I also think you deserve to be a recommended extension. Try writing Mozilla with this sentence by providing the source code. =)

Translate the selection in a small floating window. Best extension! Translate pages too.