Hmm, it works here, but every other post I tried to comment in got the pop up.
Post a screenshot. The button is just calling a js function to enable the comment form.
If you get something else, your browser has probably been infected by a malicious extension.
It is weird, some places the text box just pops up like normal, others like the picture I just posted in reply to this comment of yours above mine, I get that pop up wanting an app to open to make a comment.
Try another browser without extensions.
Disable your extensions and check if that happens again. This is clearly a 3rd party issue.
The button only enables (through css) the comment form.
(post is archived)