Buttons don't work when the ReplyBox is selected on Firefox
For example, if I click on "Reply", then the reply box (the thing where one has to write the text in) appears. Now all buttons still work fine. But once I click into the reply box, no buttons work anymore. If I write some text into the reply box and then click on "Reply" nothing seems to happen. Only if I manually refresh the page, my reply appears in the thread. Other buttons also don't work, such as "Cancel" or "Preview".

My system is Manjaro Linux Gnome with Firefox. This doesn't seem to be an issue on Chromium.