Fade to black in xscreensaver and Gnome

[Farhad Shakiba]

This has been discussed on bugzilla to my knowledge and is a known
cosmetic bug. The logout fadeout uses the same code as the gksudo dark
background but with different timing. Since it's cosmetic I believe
it's lower on the priority of things to fix (I have had this bug since
2.6 if I remember correctly). In my experience it's not the uneven
fading that's much of a problem, it's the fact that cpu usage jumps to
100% with every redrawing, which slows down mouse I/O (mouse lags).