I have a little problem with Firefox, when I'm writing something in other language besides Portuguese (especially when I write here at H&E) it shows error marks under the words, now this is not something major but it's pretty annoying to me, so could anyone tell me where to shut it off.

I think you might have to download the dictionary of the language you speak mainly from the Add-ons site.

Thanks I just did that.

And are the red lines gone?

Yup they are, as I said before thanks for your advice.

No problem