How to make a cube with the world editor? I can't find a suitable tool.

How to make a cube with the world editor?
I can't find a suitable tool.

 

For a cube you can try copy and pasting one of the already existing ones and putting it there. Unless you wanna make one out of terrain in that case go into the last button on the list. It looks like 2 mountains and it has 2 tools above it. And then you can easily figure it out from there. If those cubes cant be selected specifically go into the forest editor and use the select option then you can select it. Or you can use the paint forest tool with the correct item selected in that little menu that pops up when you go into the forest editor mode.