olivewhite wrote:It seems there is no menu slim DOM element in the Firefox inspector.
Yup, but unfortunately that doesn't say much. It just tells me the topbar menu is not there, which I can see in your screenshot anyway. As mentioned, it works fine in latest Firefox/Mac here:
I also checked FF 57 on browsershots.org, although that is not Mac:
http://browsershots.org/screenshots/76a ... 1c4b7b2116
mjau-mjau wrote:What OS are you? Looks like Mac. Your screen supports "touch"?
Looks to me like it, for some reason, thinks you have a smaller screen and/or is a mobile device.
As mentioned above, what I can almost say for sure, is that it looks like there is something with your browser that makes X3 think it is displaying on a small and/or mobile and/or touch screen. I would start by trying to open in Firefox "New Private Window", and then I would also check if could be related to Firefox plugins/extensions. Then I would try from a different machine altogether.
I wish I could say it's a bug, but it doesn't seem logical and I can't reproduce it.