My development machine, my hobby project build server, and my gaming PC are the same computer. This poses a problem when my build server wants to start compiling a huge project while I'm playing a multiplayer game.
This little program solves the problem. Just have the build process (or some automated setup script that runs every so often) run ParentToBackground.exe BuildServerExecutableName.exe and the builds will be slightly slower but you'll be able to play video games or use Visual Studio uninterrupted.
Disclaimer: This program does use an undocumented Windows NT function and some undocumented enumeration values, so it's very likely to break after a Windows update. However, the function calls used in this program worked on Windows Vista and they still work on Windows 10 Creator's Update.