Hi emuola,
You don't need to add anything to advmenu.rc
Advmenu will use the modeline currently assigned to the X system. This one is defined in etc/x11/xorg.conf. You need to place a 31 kHz modeline in there. Use the resolution 648x480, there's a good reason for this. This should be automatically done by Switchres when you select your monitor type from gasetup, but the current version on the live-cd does not support the new monitor presets. An updated version is coming soon.
Ok, thanks again Calamity I think I'll wait for the next live-cd.
One more thing: The reason I asked this in the first place was that I first had the advmenu with 648 x 480 (later switchedto 320 x nnn). The advmenu was ok, but the problem was that all the games that were more or less 320 x nnn were "squashed" from the right edge pretty badly. The only way to correct it was to adjust the display settings from the panel of the display itself (vpos/hpos/ etc).
I figured that I can only setup the display settings once (the m3129 does not havememory for different presets?), so that I really cannot have the advmenu in 648 x 480, becuse the games won't use that mode.
So: is there any way to get the advmenu "flicker free" in 320 x nnn?
Am I completely lost here or what?
As you can see, I'm really no pro here