Using xorg-x11-server-Xorg-1.5.99.901-5.fc11 on x86_64, C-A-B no longer zaps X. I'm told this wasn't an intentional change, so there must be something strange going on. This is mildly annoying when I boot my machine with the KVM switched away, and GDM comes up at 800x600. Normally I zap X and it happily restarts and gets the right resolution. I'll happily support disabling C-A-B by default if there's a better solution for this use case.
NOTABUG, upstream changed to DontZap enabled by default.
What is the xorg.conf syntax to enable it again, just for reference?
xorg.conf(5) Option "DontZap" "boolean" This disallows the use of the Ctrl+Alt+Backspace sequence. That sequence is normally used to terminate the Xorg server. When this option is enabled, that key sequence has no special meaning and is passed to clients. Default: off.