Earlier quoted context omitted.
I really liked Windows 7's per-app volume mixer [0] (Windows 7 is the last Windows I really used, not sure if they kept it or not in later versions). I'm sad that the idea hasn't made it to other operating systems, with a system level API to allow for setting volumes independently on sound streams in different apps (an app could expose any arbitrary number of sound streams - most apps would likely have just 1, but br…
I may be misremembering, but I have a feeling the per-app volume mixer was available all the way back in Windows XP. Possibly sound-card dependent? An app called Jack OS X does the job on Mac: http://www.jackosx.com/
That panel on XP (and before) only permitted per-device volume control.
For reference see [1] at around 04:00 and Larry Osterman's posts from September and December 2005 [2][3].
[1]: http://channel9.msdn.com/Blogs/scobleizer/Steve-Ball-Learnin...
[2]: http://blogs.msdn.com/b/larryosterman/archive/2005/09/19/471...
[3]: http://blogs.msdn.com/b/larryosterman/archive/2005/12/15/504...