Hi, I have jailbroken my iphone and unlocked it, everything works fine ok except for the springboard where there is a black line at the bottom of the screen of about 1cm. That problem won't show if I open an app or go to the settings. My iphone is a 3GS, 5.12.01, iOS 4.1 jailbroken with green poison (activated) on a mac, unlocked with ultrasn0w.

Here is the screen : http://yfrog.com/42img0405p

Does someone have this problem and know how to fix it ?

Your reasoning is not accurate.

1% percent more of 10% is 10,1%, the amount doesn't double.