Can I run dconf-editor for a different user? (user gdm), or find some other magical way to disable the notifications that pop up while logging in?
In particular there is a persistently annoying notification that my mouse battery is low. I'm fairly certain it is really the keyboard battery it is talking about, but the dadgum keyboard has a red light that comes on when it actually needs charging, the gnome check is totally bogus and starts weeks before the keyboard actually needs to be charged.