As I can see, we have only torus there. There should be more imho. I suggest torus, cube, sphere, grid, text3d. The default primitive those to be chosen in wz prefs.

added cube and sphere primitive.
To change use the shortcut 'v' in 3d view to swicth shape.

Yey! Works fine. But usage is rather tricky. I had to edit my wire.txt (I have custom Blender-like navigation shortcuts).
Maybe you could add a "MatPreview" button next to CalcSlowOps? That would be great for noobs who don't use wire.txt.

no you just need to recompile all (rebuil all)

It seems that I don't have this option in VS Express. Shall I rebuild all the projects in the solution?

Found it! Rebuild solution.

Yes. It works without wire.txt! But if it is custom, then I'll have to update it anyway! Thanks.

yes because there is a new shortcuts

Yeah. Thanks again. I guess it's enough for now. So... It's done.