Bug#488277: I have exactly the same problem

[Alex Deucher]

On Tue, Jul 1, 2008 at 3:56 AM, Eric Valette <eric.valette at free.fr> wrote:
> Alex, Julien
>
> First thanks for your help.
>>
>> The modes in your screen section apply to all outputs.  The ones in
>> your monitor sections only apply to the specific monitor in question.
>>
>
> I removed the mode lines from the screen sections. I did not add them back
> to the monitor section as they are correctly probed by the driver.
>
> Result is no change. The display on the external lcd is only a portion of
> the whole 1400x1050 resolution. Explicitly setting the resolution of the
> LCD, does not change anything. I still have to resort to the script docked
> to have a correct display.
>
> If you have any other suggestion, please tell me I will give it a try.
>
> NB: I would prefer to have a single configuration file for both config.
> Using xrandr or a script like today is ok. With kde4, krandrtray will enable
> to to this graphically.

you'll need to specify a preferred mode per-output if you don't want
to use the default preferred modes for each monitor:
http://wiki.debian.org/XStrikeForce/HowToRandR12

Alex