Are you sure that there were different icons in 2.x? I think all (desktop) Windows versions used the following icon: https://github.com/piwik/piwik/blob/2.x-dev/plugins/DevicesDetection/images/os/WIN.gif

But I agree with you that it would be better if every Windows version would show its own logo.

@sgiehl is there any reason that all versions are mapped to "WIN"?
https://github.com/piwik/piwik/blob/2.x-dev/plugins/DevicesDetection/functions.php#L254-L266

the icon you linked was for winxp in piwik2.1x (if i guess right..)
it is not that one that is diplayed here in piwik3.x for win xp, 7, 8.1, 10
the icon displayed here for win xp, 7, 8.1, 10 in piwik3.x is that one:
https://github.com/piwik/piwik/blob/3.x-dev/plugins/DevicesDetection/images/os/WIN.png

@github-hbr If I remember correctly there was and still is only one icon for all windows versions. I just changed it from the old xp-like logo to the new WIN10 logo.
But it may be nice if every Windows version would have its own logo.

We used to have special detection for Windows in device detector. Each Windows had been reported as its "own" os. As that was not really correct (os is always Windows and version is XP, 10, 7 and so on), it has been changed in device detector and in Piwik. All windows versions are showing the same icon in Piwik 3.

Maybe it's possible to use a different logo for the versions and fallback to the current logos if there is no version specific logo.
https://github.com/piwik/piwik/blob/3.x-dev/plugins/DevicesDetection/functions.php#L283

I'll look into it, if I have time.

I'm afraid there is no easy way to get the version.
If anyone has a solution I'll contribute the icons.