Mouse scroll does not work on Fx48

[pzhg]

I cannot scroll the vertical tab bar with my mouse middle wheel after I upgraded to Fx48. I am not sure this is an issue of TK2 or not but it is likely a problem of TK2 because I've tried to disable other add-ons, no help.

BTW I am using windows 10 with Fx48.

[dahorak]

I can confirm this on on Fedora 24 - firefox-48.0.1-1.fc24.x86_64.