We have slowly been putting infrastructure in place for this. There is a lot yet to go. I consider this to be a multi-release effort (actually the infrastructure so far has been going on through a couple releases).
Basically all of the tight interactions between the lock screen and WindowManagerService/PhoneWindowManager need to be removed and turned into an IPC protocol. They need to be made robust in order to deal correctly with situations like the lock screen process disappearing.
Honestly this is something I would recommend against working on. As I said, there is ongoing work to move towards that. In fact every release seems to have a fair amount of work happening in the lock screen, so it would be painful to do such a major change in that code in parallel with ongoing work there for the current release.
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Dianne Hackborn
Android framework engineer
hac...@android.comNote: please don't send private questions to me, as I don't have time to provide private support, and so won't reply to such e-mails. All such questions should be posted on public forums, where I and others can see and answer them.