Seem like not happening on me. Maybe try using external image host (like shota.nu) next time?

Originally in that post, I commented that the bug is caused on Firefox nightly. But later, I find out the bug is caused by misconfigeration of no-scripts, so I detete the comment and post another one.

Maybe I should edit the comment next time. Sorry for inconvenience caused.

I reproduce it with no-script addson enable. Should be some wrong setting in the extension cause the problem.

after a few testing, it seem it is caused by no script of my browser. Thank for your reply.

Go to your profile and the bug is reproduced.

Yes, you can get it at here

No. I am too broke to buy the license of gnome :(

Thanks for reply. Report on bugzilla

Here is the video

As you can see, scrolling is available for webpage, but not in sub-menu.