106.22 KB, image/png
User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:38.0) Gecko/20100101 Firefox/38.0 Build ID: 20150117030203 Steps to reproduce: opened nightly already logged into yahoo mail via cookie, looked at tab. mail.yahoo.com Actual results: right scroll bar missing, page doesn't look right. Expected results: the page is longer than the viewport, so it should have shown a scrollbar.
Created attachment 8551445 [details] 38.0a1-trunk-rt-scrollbar-missing-page-renders-wrong.png screenshot
Does this happen every time you load your webmail? Does it happen in a new profile?
it does not reproduce. flaky bug. good question. I discovered this right after posting this. I must have got scatterbrained with the number of things happening in these few days.
But reports are great, it would be very preferable to have reproducible steps before filing bug report