Pitch visibility in Drum Editor - how is this meant to be used?

I’m starting to play with the Drum Editor and Groove Agent and I’m trying to figure out the Pitch Visibility feature and how it’s intended to be used.

The Manual says, “the Select Pitch Visibility Options pop-up menu on the drum editor toolbar allows you to determine which drum sounds are shown **in the drum sound list.”*
.… but the Drum Sound list appears to show all the drum sounds.

In this example I have a piano with five notes in a phrase: C, C#, F, G, and G#, and the piano track is selected. In the Drum editor I have Pitch Visibility set to "Show Drum Sounds in Use By Instrument"and it’s grayed out but the five notes in question are shown as diamonds in the Drum Editor. Of course pianos don’t have drum sounds but what would be a good example where it wouldn’t be grayed out?

If I select The Groove Agent instrument itself the list doesn’t change, but the menu option is no longer grayed out.

Besides the User Manual, which is very terse, does Cubase publish any documents showing how these features are actually intended to be used? Searching for stuff like this in tutorials and YouTube videos is very random and hit-and-miss. Is there a systematic way to find answers to questions like this?

Thanks in advance.