Odd Windows Discovery

Did you know that Windows doesn't always run the program you tell it to run? You can double-click on an executable and some other executable might be run instead.

I've learned recently that Microsoft intends to discontinue MSPaint for some inexplicable reason. It doesn't require any maintenance to keep; they could easily have abandoned all future development and left it as a relic amongst all the other relics cluttering up the code base. It would've gone on working for many years to come.

But no, they decided to actively pull the plug on it, which inspired me to fire it up. Not the current one, but an older version I happen to have archived from Windows 98. I run it and, much to my surprise, it looks exactly like the one from Windows 7, my current system.

Suspicious, I look up the process in Task Manager, and it points me to MSPaint.exe, not PBrush.exe. After trying some other old legacy Windows software, I discover that the same trick is performed with Notepad, Calculator, and CD Player. Wordpad is launched when I try to run Writer.exe (though Writer gets an unseen process). Interestingly, MPlayer.exe does not try to run the modern version of Windows Media Player and just crashes, though after forming a window. That may be just me, though; I don't have the modern version on my PC.

I also discovered that this behavior persists even after the old programs are moved to other directories or renamed. This means that every time you run a program, a piece of code in Windows has to check it over to see if it's some archaic came-in-the-box piece of software that it would rather run the new version of. Every. Single. Time.

Billions of times every single day this little unseen snippet of code monitors program execution, waiting for the vanishingly small number of times that it can save someone from using an outdated version of paint.

Naturally, I have to wonder at the purpose of this piece of code. How long has this been a part of Windows? What prompted it's creation? Does somebody choose for it to continue to persist or is it mindlessly included because the effort of discussing it's existence is greater than whatever tiny change is required for the next version? Will it, too, meet the chopping block when it finally requires real work to keep it and nobody can remember why it was there in the first place?