I have an interesting observation. If I open a terminal, without virtual keyboard pops-up, the screen jitters. But as long as the virtual keyboard pops up, the screen is stable (no jittering). Next I open matchbox-keyboard, and the same happens. As long as the keyboard is active (on screen), the screen is stable. But as long as I closes it, it jitters.

This leads me to think it is not purely a hardware problem (though I have not seen this in past 9 months). Hopefully there is some software fix possible (I will try to see if I can make some keyboard hidden but active).

Edit 1: Keyboard cannot be made hidden. More observations: some apps have no jitter problem in full screen mode (e.g. terminal, stardict, eggtimer etc), but not in normal screen mode. 2 apps appear to have no jitter problem even in normal screen mode (galculator and maemopad+). FBreader has jitter problem even in full screen mode. Any system expert can help to fix this with software patch please?!