This is intended as a hidden doorway, but it's a reasonable way to design closet doors. That's because you're not expecting furniture to be placed in front a closet door. So, adding shelving makes use of that otherwise dead space.
DIY Tutorial for hidden door bookcase. Can put valuables behind there not sure if I should put it in crafty, but there’s part of that loves the idea of having a secret room :D I’d make it into a little reading nook @ Pin Your Home