Showing Windows apps in Parallels Coherence with mac-style title bar with red/yellow/green dots on left?
I always found changing between Mac and Windows extremely annoying for that reason as well, and was totally excited to find out that you can close any Windows window that has an X, by simply double-clicking the far upper-left-hand corner.

I cannot say about Win10 specifically, since I don't have that installed anywhere, but I know it worked from XP, all the way through Win8.