I'm currently trying to deploy After Effects CC on our farm (osx 10.8, render nodes only, no active session), and I am stuck again with this annoying ui context, trying to communicate with the window server (This API can only be used by a process running within an Aqua session).
On (snow) leopard / CS6, setting the sudo bit did the trick (ie: chmod 4755 aerender), the aerender process was able to steal the login window, but it looks like it's not possible anymore, starting from lion :
The only way I found right now is to keep local admin session open on each render station, and force admin user when spooling jobs, but it's definitely not an option since render stations should not be logged automatically (not at all !), and impersonated jobs won't allow user granularity (no custom environment, per-user limits, access rights, storage quotas etc.)
I'm looking at PreLoginAgents (https://developer.apple.com/library/mac/samplecode/PreLoginAgents) since it seems to be a way to work around this issue, but it looks like shooting a fly with a bazooka … any trick or advice would be greatly appreciated !
Thanks in avance,