Hide all objects / show terrain only

There needs to be a way to Hide All Objects / Show Terrain Only when editing a map. When my maps are being developed I will often want to adjust specific parts of the terrain in detail, but there are objects in the way.
A “Show Terrain Only” button on the Edit Terrain Menu (similar to the Clear terrain button) would be a simple way to add this option. An extension would be to allow filtering the visibility of specific object types, a bit like showing/hiding layers in a graphics edito.