Created attachment 8761433 [details] example.png User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:47.0) Gecko/20100101 Firefox/47.0 Build ID: 20160604131506 Steps to reproduce: started firefox and found a page where the Actual results: the scrollbar is not visible, just white space ... but its there, i can "grab it" without seeing and if i then drag the scrollbarr down or up the page moves as it should i have tried to set different gtk themes, no difference. tried a new profile. no difference. tried with updated beta release, then it worked! it is in gnome gtk 3.20 Expected results: the scrollbar should be visible.