You can see the windows here:
http://binged.it/KatbWY
It doesn't really make sense to prevent neighbours from building because one property owner/developer decided to put in windows near the property line. Does he expect that the CD Plus site should be limited to 2 floors permanently because he has a third storey window?
Another claim was that the new building would block visibility of the Tramway Building, but it's pretty clear that there are no interesting features to be blocked on that side.