One other way to get door out relatively undamaged which i have done a few times - with a view to refitting it with a new lock mechnism.
Using a hacksaw blade saw through the fixing screws that are securing the door & frame in place = Not an easy job and not a quick one either but it does work.
An electric reciprocating saw saves a lot of time and effort.
Like Steven said before me - 'its rather complex'. . . .
Sojace
December 2010