I have no experience with the technical side, but aren't most of the problems you describe inherent to pre-login screens? Shouldn't the login screen have different power management options than a desktop after login? After all, what if different users have different preferences about what should happen when they close the lid? There is no way that the login screen can predict which user is going to log in and adjust its settings on that, so it'll have to use some default/system wide setting. There's _always_ going to be two or more sets of policy, right? I believe this is even true for gdm - its preference come, IIRC, from the special account 'gdm', not from some user that might log in. (That aside, without being able to oversee all possible uses of the display manager, I could on first sight even defend not having a power policy at all, as there is no risk of data loss and the login screen will in most cases only be shown for a short period anyway.)