From Bugzilla Helper:
Using gdm to login doesn't touch X. Logging out from KDE or Gnome, on the
contrary, restarts the entire X. I'd assume that this behavior is
suboptimal and wrong. X is big and should be preserved in memory. This
causes huge memory stress for the system and the blinking is not very
healthy for the monitor.
Steps to Reproduce:
1. Use graphical login
2. Login, then logout...
3. Watch for pid of X...
Actual Results: X gets restarted - its PID changes and the screen is
Expected Results: Preserve X from restarting and video mode from changing
back and forth.
There's nothing to be gained by keeping X in memory, and no monitor that I know
suffers adverse consequences from swapping video modes (since all PCs do this
every time they're restarted, and many PCs are power-cycled several times a day
for years with no damage to the monitor). The restart lets new logins use a
"clean slate," which may reduce memory usage, probably increases stability a
bit, and keeps users from playing dirty tricks on each other.
Of all your arguments I only agree with "clean state". As for dirty tricks,
what could be worse than restarting X on a system with multiple remote X
terminals? Plus, log out does take a few seconds to comlete even on a modern
system with Athlon 750 MHz. I suppose 90% of this time is restarting X.
RedHat has two options - graphical and text login. I think they must have a
meaning besides esthetic one. Text mode should be used to achive "clean state"
and prevent dirty tricks. Graphical mode should be used when X needs
uninterrupted execution as on systems with multiple X users.