User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:37.0) Gecko/20100101 Firefox/37.0 Build ID: 20150415140819 Steps to reproduce: Open the option windows; Select a tab (i.e. the "privacy" tab); Change something; Close the option windows; Open the option windows again; Actual results: The last tab used in the option windows is now blank (grey, in my case); All other tabs in the option windows are ok; To get around the issue, select a tab you don't want to use right now, close the option windows, open it back. The current tab will be the last selected and will be blank. Now, choose the tab you really wanted to use and it is now visible! Closing Firefox didn't solve the issue. Have not reinstalled Firefoxm though... Expected results: The option tab should not be blank.

Is this still reproducible?

In bug 1012368 it was decided that this will not be supported.

but a workaround is mentioned in bug 1012368 comment 36