Raspberry Pi with original Pi Display and Jivelite

Hi,

What is the grid size that needs to be set when somebody uses the original Pi display? This has a 800×480 resolution, but if I set a grid size of 800×480 the lower part of the screen does not react to touches.
I have a fresh install of the image that is customized for this display, in my understanding this should include all the settings other than language, but something is not ok. Can anyone point me to the right direction?