Comment Re:Erm... (Score 1) 365
Of course they wouldn't need to fork the code - it's possible to make use of new features in the operating system if available but fall back to the older methods.
Requiring Windows Vista/7 specific features will lock the browser to Windows and will make porting to other operating systems, should they choose to, difficult. As I said, other browsers have no problem making use of specific operating system features for acceleration and still being cross-platform.
Windows XP has a 25% share so is a long way from obsolete.