Shouldn xscreensaver disable Ctrl-Alt-Backspace while the screen is locked?
Yes, it probably should; unfortunately, that’s not possible with current versions of XFree86/XOrg. If you want to disable the Ctrl-Alt-Backspace keystroke permanently, you can set the DontZap flag in your /etc/X11/XF86Config or XF86Config-4 file. See the manual for XF86Config for more details. Likewise, it’s not possible for xscreensaver to prevent virtual-terminal switching (Ctrl-Alt-F1, etc), so don’t leave yourself logged in on a non-X console and expect xscreensaver to be able to protect that console too…
Yes, it probably should; unfortunately, that’s not possible with current versions of XFree86/XOrg. If you want to disable the Ctrl-Alt-Backspace keystroke permanently, you can set the DontZap flag in your /etc/X11/XF86Config or XF86Config-4 file. See the manual for XF86Config for more details. Likewise, it’s not possible for xscreensaver to prevent virtual-terminal switching (Ctrl-Alt-F1, etc), so don’t leave yourself logged in on a non-X console and expect xscreensaver to be able to protect that console too… Likewise, the magic OOM-killer keystroke (Alt-SysRq-F) might target and kill xscreensaver, and there’s no way for xscreensaver to protect itself from that, either. It’s just another one of those little land-mines that the kernel developers seem to like to leave scattered around that completely bypass the security of your X11 console. (Disable it globally with sudo ‘echo 0 > /proc/sys/kernel/sysrq’).
