Not much if the developer stays to the standard UI. How do i know? First of all, i've written my own android programs. Running on a new version is generally no

Not much if the developer stays to the standard UI. How do i know? First of all, i've written my own android programs. Running on a new version is generally no problem, there may be some minor changes that the developer docs usually tell you about. Nothing fancy that can't be done in a few minutes. Second, when 2.2 was released most programs ran out of the box on 2.2, there where no app updates for a few days. Out of all the programs i have installed (there are quite a lot) only one had a minor graphic bug, that has been fixed now. Don't know what was causing this, though. When you say "OpenGL is for platform independence" you are right. But if you look at all the versions, and _especially_ the vendor specific OpenGL extensions, you'll see that OpenGL is quite fragmented itself. Also, it doesn't abstract away screen sizes and such.