Is it possible to always keep selected item in the middle of a listbox? If the user selects an item, I want to scroll so that the newly selected item is in the middle.
I guess it want be possible for the 'edge cases' (the first and last few items), but that's ok.
It is possible with couple of lines of custom code. Here's a discussion of a sample implementation. You might need to tweak it a bit to account for even number of items, insted of only odd number, but the general idea is the same.
David Anson posted some articles on his blog that might help you here: Part 1 and Part 2. He gives an extension method that centers an item in an List Box. You might be able to build on that.