The default XF86Config file on Redhat is XF86config-4.  Can't tell you why.... 
anyone know?

If there  any modeline entries in XF86config-4, that would explain why you are 
unable to toggle between screen resolutions, if you don't have any defined.  
About 3 hours of aggravation before I discovered I had been editing 
XF86Config, instead of -4

Kyle Faber 
EMR Data Services


On Thursday 03 October 2002 07:53 am, Ed Skinner wrote:
>      When I use a projector with my RedHat 7.2 notebook,
> the projected video wiggles in vertical bands. In the past,
> the key combination that toggled the video output, if I
> cycled through all possibilities once, would solve the
> problem. Now, however, this key combination doesn't appear
> to do anything at all. Completely non-functioning. (It's
> been months since using the projector: I'm not sure what
> may have changed but, for one thing, I'm using a custom-built
> kernel instead of the stock RedHat kernel. I changed the CPU
> type to Coppermine and enabled ACPI and turned off APM BIOS
> [which appears to have had no effect on anything].
>      I think the swimming effect might be a refresh-rate
> conflict between the LCD and the video projector. Can I
> solve that in XF86Config (but what is XF86Config-4 for?)?
> Maybe one of the following needs to be changed? Suggestions
> would be most welcome.
>
> # [snipped from /etc/X11/XF86Config, nothing like it in XF86Config-4]
> # 1024x768 @ 100Hz, 80.21 kHz hsync
> Modeline "1024x768"   115.5  1024 1056 1248 1440  768  771  781  802 -HSync
> -VSync # 1024x768 @ 60 Hz, 48.4 kHz hsync
> Modeline "1024x768"    65    1024 1032 1176 1344   768  771  777  806
> -hsync -vsync # 1024x768 @ 70 Hz, 56.5 kHz hsync
> Modeline "1024x768"    75    1024 1048 1184 1328   768  771  777  806
> -hsync -vsync # 1024x768 @ 76 Hz, 62.5 kHz hsync
> Modeline "1024x768"    85    1024 1032 1152 1360   768  784  787  823
> # 1024x768 @ 85 Hz, 70.24 kHz hsync
> Modeline "1024x768"   98.9  1024 1056 1216 1408   768 782 788 822 -HSync
> -VSync