Implementation tasklist for better update experience

Fedora Process

Enhancement (anything non-security) updates are scheduled for once a month (at least for core, extras might be more flexible).

Separate download process from install
Add functionality to yum to detect what packages are currently running (doable at high confidence for c/c++, e.g. scripted plugins are a hard case, ignore for now)
PackageKit daemon wraps said functionality
For running apps (apps, i.e. open X windows), show a dialog indicating they need to be closed (also, window manager adds (Update Available) or something to title)
On clicking "Apply", pk-update-icon sends a close request to all windows corresponding to that process it finds (in sequence?) (TODO: standard application dbus interface?)
When application is closed, packagekit starts updating that app (+ dependencies)
Application is restarted (pick first .desktop file in package? eww. require backporting GNOME Shell application tracker as dbus service?)

Other notes: Should block application relaunch during updates too; show the user the updater dialog

All desktops are logged out, system switches to gdm (or plymouth?)
gdm shows updater screen
perform a "dependency reboot"; e.g. if kernel/init/dbus, do a full reboot. Otherwise, for system daemons do "service foo restart".

Similar to running app - if it's on the system it's implicitly running, basically. It's either a crucial library like glibc, a key system daemon like NetworkManager, or a general program like curl that we can't know reliably when it might run.

By default, apply automatically when safe (shutdown/reboot, configurable timeout (one week?)). Note availablity of updates at context switch time (screensaver, gdm). If configured to prompt, do so of course.