I see, thanks. It always seemed odd to me that they took that approach to solve the problem. Simply because so many minor tweaks to APIs do cause problems with

I see, thanks. It always seemed odd to me that they took that approach to solve the problem. Simply because so many minor tweaks to APIs do cause problems with old apps, or cause massive headaches when various quirks have to be maintained for decades. Whereas a "Classic mode", "WINE", or "Virtual Machine" style mode would seem to solve the backwards compatibility thing in a much more containable way - apps still run, the old APIs stay frozen in the custom environment but deprecated/removed outside, new developments can use new APIs without being saddled with the old. Even though the compatibility environments have to be kept around forever, now you've only got a few API interfaces to renovate (connecting the classic environments to whatever new Windows APIs exist), instead of thousands. I guess it's not as simple as that, though.