Look at the picture below.
These are the Team System tests results I run today. Why the heck is more than half of the window empty (huge red rounded rectangle) ? Instead, the grid could perfectly fill the empty space and thus reducing the stress on my mouse wheel.
I have no idea why there is an empty space but [MS] developers are often keeping dialogs fixed and small (how much time it took to get resizable dialogs, such as Add References... one) and it seems the same happened to this unfortunate form (if you have a screen bigger than 15" that is). If you look at the bright side, at least grid's horizontal expansion is there.
Is this going to change in Visual Studio 2008? Judging from beta 2 - the testing UI has been redone to some extent and this grid doesn't appear anymore at all.