Tor Browser 5.0 Can't Disable Taskbar Lists

In Firefox the preference browser.taskbar.lists.enabled toggles the start menu task lists in real time (i.e. changing the preference immediately adds/removes the button in the start menu).

This preference doesn't seem to work in Tor Browser. I'm not able to remove the task list.

Tested on Windows 7-64 bit, tried Tor Browser 4.0 and 4.0.1.

Trac:
Username: ZcbCkyj5