@bluetale said:

thx
But I receive an error if the faces normal is parallel to Z_AXIS.
I have added the following lines and it seems to work, but is it the correct solution?

if !vector.parallel?(Z_AXIS) then > up = Z_AXIS > else > up = Y_AXIS > end

It's a good trap! 😄
PS you don't need the 'then' and perhaps more 'simply' put

if vector.parallel?(Z_AXIS) up = Y_AXIS else up = Z_AXIS end

No. You can stack your own Ruby Tools - but you can't stack the native ones unfortunately.
You've have to recreate the tool.

@bluetale said:

@dan rathbun said:

I think you need to use MF_CHECKED for the active item, and MF_UNCHECKED (or MF_ENABLED ) for the other two.

I tried it, but it did not work. Is there a way to get a radiobutton-like behaviour of toolbar-buttons?
..snip...
Is there a way to get such a behaviour as explained above for the mac-version?

There may be a bug in the Mac version.
I see this issue has been discussed in more detail in your more recent topic:

Toolbar Win vs Mac
http://forums.sketchucation.com/viewtopic.php?f=180&t=32626

thanks for your advice, I will try your suggested methods.

A polygon mesh is all just triangles?
hmm... That would be interesting for the Normal Probe I just made...