X10. Display problem
As pointed out above, the only way you can see an exposure variation on the screen is to use the "M" Manual mode.
My display does not change in M mode. The display is always set to show a reasonable image. If it varied with camera settings you would not be able to view an image in under-exposed situations.
What's wrong with:
1) Taking an image and checking it back, with the histogram turned on for playback
2) Using exposure bracketing.
Silkypix tutorials at: http://photo.computerwyse.com