So I was making a Great house upon a hill that had snow (one layer of snow) and then, suddenly I placed a slab where once a layer of snow way, but (and here it happens) the snow stayed the slab was there, I could see that clear. but the snow was there too 'impossible' I shouted, I was furious at a little bit of overseen bug I pressed "Esc" on my mighty gaming keyboard and headed over to the "Minecraft Bugtracker" and wrote this story because I am a bored kid.

-the actual bug: so if you place an upsidedown slab on the side of a block where there also is snow on the ground it gives you the illusion of snow but it doesn't exist: