Showing four options in a menu?

[Geoff Canyon]

For displaying a simple binary choice in a menu, a !c checkmark works well.
But in Navigator's property menu, there are four possibilities:

1. the property is not boolean -- display nothing with the menu.
2. the property is boolean and is true for all the selected controls --
display a !c check.
3. the property is boolean and is false for all the selected controls --
display ???
4. the property is boolean and is false for some of the selected controls
and true for others -- display ???

Is there any way to handle this without a sub-menu? It would be nice to be
able to set booleans from the menu just by selecting them instead of having
to mouse onto  a sub-menu.