Peabody wrote:

You can't do what you're trying to do. This question comes up from time
to time. The LCD must be driven at its native aspect ratio in order not
to get either letterboxing or stretching. Your choice of display modes
is fixed by the laptop manufacturer. The only widescreen resolution
offered on the LCD is the native resolution. The other (4:3)
resolutions are provided solely for compatibility if you're running old
games software or using a mirrored display configuration with an
external 4:3 monitor.