Comment 18 for bug 1484157

I have the problem too, in Thunderbird on Ubuntu 18.04 with Unity on one system, another one works fine.

Interestingly, it only seems to affect the address field when writing a new mail. With our German keyboard, we need AltGr+Q to enter '@'. Other text fields are not affected.

I've tried the workarounds mentioned here, but that did not help.

Do you have any more ideas?