[kmontrose]

Such as?

App compat's out (ie. "Run this program in compatibility mode for"), too many libraries. They'd never get an accurate enough list of affected programs.

They can't change the reported OS name, too many apps display it; and it'd be crazy weird (a bug for all practical purposes) to have programs claim they're on "Windows 10" while the box says "Windows 9".

Probably can't change the format of the name either, ie. "Windows(tm) 9" or "Microsoft Windows 9" or whatever; I bet tons of apps just check for "Windows " as well.

It's an unfortunate choice, but I don't really see an alternative if they wanted a numeric version number.

[harryh]

Spend some time reading The Old New Thing. Microsoft's ability to deal with buggy applications is world class. It's one of the core competencies of the Windows team. There are not too many libraries.

[Arnavion]

kmontrose is right. App compat is an application-level thing, not a library-level thing. Applications can load libraries dynamically even if they didn't want to (shell extensions are the classic example here).

Do you want explorer.exe to think the OS is named Windows 10 because it loads a library that requires the compat fix?

[eurleif]

How about "Windows Nine"?

[kmontrose]

Localization probably kills that, since this is displayed to users a not-insignificant amount of the time.

"9" is pretty well universal (I know, not strictly, but for software Arabic numerals are kind of assumed knowledge); "Nine" on the other hand isn't something you know without being able to read English.

(Having been through a pretty big localization project recently... this stuff sucks. So much. All your assumptions start breaking.)

[harryh]

Indeed this would also be a great solution and probably easier than dealing with compatibility issues one at a time.