Share button - Tor Browser 4.5.3 -> 5.0 Mozilla Updater
A user (iddqd) joined the #tor IRC channel questioning the inclusion of a 'share' button in the tor browser.
Unable to see a similar problem, we suggested something had changed in the users settings. However upon further investigation I was able to reproduce the buttons appearance by upgrading from 4.5.3 (linux, 64bit, en_US) tor browser to 5.0 through the native mozilla updater.
The button appeared to be greyed out and unusable however other users are reporting slight differences with it's appearance to them and their ability to interact with it.