Window Lock has a large window covering the front of the lock. Seems kinda generous, almost -putting all of the gubbins inside on fairly clear display… and yet in spite of that, it’s a really fun puzzle!

The window gives you a clear view of what’s stopping the shackle from opening, and you can see what’s blocking that in turn... A little manipulation will get things to begin moving and then it gets interesting, because there’s no apparent way to do what you want to do… and there are some spare bits and pieces inside that lock that don’t appear to perform any useful function…