ctrl-alt-+ doesn't work for me

[D. Hugh Redelmeier]

I am encountering a video bug on my Fedora 13 desktop using the Radeon
driver.  Once in a while, the screen goes blank in a way that hitting
a key or moving a mouse does not undo.  I don't think that this
blanking is aligned with normal screen blanking.

I was given a suggestion.  When this blanking has happened, I ssh
into this machine from another and issue the following commands.  The
screen will then unblank:


    DISPLAY=:0.0 xrandr --output DVI-1 --mode 1280x800
    sleep 5
    DISPLAY=:0.0 xrandr --output DVI-1 --mode 2560x1600

But that's not what I'm actually writing about -- that's just
preamble.

I want to be able to use ctrl-alt-+ or ctrl-alt-- to cycle between X
modes (resolutions etc).  This should allow me to fix the display from
the keyboard of the afflicted machine by blindly typing ctrl-alt-+ twice
(with this display there are only two modelines synthesized by X).

ctrl-alt-+ does not work for me on F13.  I don't know when it
disappeared.  Perhaps when ctrl-alt-backspace was retired.

After spelunking, I find that there is an xorg.conf option "DontZoom"
that is similar the "DontZap" (the one that can allow
ctrl-alt-backspace to work again).

Of course that means you need an /etc/X11/xorg.conf, something that
has mostly disappeared with recent versions of the xorg system.  You
can generate one by:
	yum install system-config-display
	system-config-display --noui

Then you edit in this section:
    Section "ServerFlags"
	    Option "DontZoom" "false"
    EndSection

There ought to be a better way just as there is for DontZap.

Worst of all, it still doesn't work.  Even though /var/log/Xorg.0.log
shows that X accepted the option.  I tried xev to find out what
keysyms were being generate:

    KeyPress event, serial 33, synthetic NO, window 0x3800001,
	root 0xf9, subw 0x0, time 23518785, (1400,548), root:(1662,639),
	state 0x10, keycode 64 (keysym 0xffe9, Alt_L), same_screen YES,
	XLookupString gives 0 bytes:
	XmbLookupString gives 0 bytes:
	XFilterEvent returns: False

    KeyPress event, serial 33, synthetic NO, window 0x3800001,
	root 0xf9, subw 0x0, time 23518788, (1400,548), root:(1662,639),
	state 0x18, keycode 37 (keysym 0xffe3, Control_L), same_screen YES,
	XLookupString gives 0 bytes:
	XmbLookupString gives 0 bytes:
	XFilterEvent returns: False

    KeyRelease event, serial 33, synthetic NO, window 0x3800001,
	root 0xf9, subw 0x0, time 23521050, (1400,548), root:(1662,639),
	state 0x1c, keycode 86 (keysym 0x1008fe22, XF86_Next_VMode), same_screen YES,
	XLookupString gives 0 bytes: 
	XFilterEvent returns: False

It looks as if the required keysym is being generated
(XF86_Next_VMode).  Why isn't the screen resolution changed?
Is this documented anywhere?