It seems that the recent redesign of the window that pops up when attempting to flag comments has some subtle bug: when it pops up, it does so in the upper left corner of the browser window in such a way that most of its content is outside the visible area of the window (and thus is unusable). I have to manually resize the browser window a bit, in order for the pop-up window to suddenly become centered (and fully visible) in the browser window as it was supposed to be. This happens on Firefox 52.9.0 ESR 32bit (no extensions), on Windows XP SP3 (yeah, yeah, I know, don't ask...). I'm having this problem on MSE, MO and SO, so it seems to be a SE-wide bug. Could a moderator please forward this to the SE team, or to whoever is in charge of these issues?
The above behaviour does not happen when flagging answers or questions.