Lightning 4.5a1 (Build ID 20150906030358) with Mozilla/5.0 (Windows NT 6.1; WOW64; rv:43.0) Gecko/20100101 Thunderbird/43.0a1
The App menu (Hamburger button) in calendar and task tab doesn't work. When clicking on it nothing happens. Maybe regressed by the recent changes from Bug 890332.
Backed out bug 890332 and the App menu is working again.