User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0 Build ID: 20150508094354 Steps to reproduce: Noticed the Folder Pane View - Unified Folders arrows for cycling through the different Unified Folder views were missing. Actual results: Tried to see how to turn them back on, discovered they were intentionally removed with no native way to bring them back. Found the 'Folder Pane View Switcher' Addon that put them back. Expected results: There should be a native option under the View > Folders menu to toggle these on and off.
I searched quite a bit and didn't find a bug or any other discussion as to why these were removed.