Rightclicking on chests with slabs, without holding shift, places the slabs, instead of opening the chest. You can also place a slab on top of another slab you're standing on the side of when sneaking - which has repeatedly killed my friend in our skyblock game because it keeps pushing them into the void.

Additionally, you can break half a cobblestone double slab with your hand and get the slab back.

DoubleSlabs: 4.0.0

Forge: 37.0.43

Minecraft: 1.17.1