Vidalia's torrc editor does not allow unsetting an option
I added “MapAddress check.torproject.org 1.1.1.1
” to a TBB's torrc using a text editor in order to test whether part of the ‘description’ of #4754 (closed) was accurate. Then I used Vidalia's torrc editor to remove the MapAddress line (with the ‘Apply all’ radio button selected and the ‘Save settings’ box checked), and nothing happened.