System flag for Symbols palette

Is this flag meant to work? It doesn't seem to, but perhaps I am misunderstanding how it is intended to be used.

What I tried was:

1) score for two instruments
2) enter some notes onto both staves
3) generate parts
4) select a note on bottom staff
5) Z
6) set "System flag"
7) double click a symbol in palette

I expected the symbol to appear above the top staff in the score and on both parts. Instead, all it did was make the symbol appear way *below* the bottom staff (while still being attached to the note I was attaching it to), and it did not appear in the part for the top staff.

If this was supposed to work, I'm happy to file an issue, but I'd like to understand the intended purpsoes first.

And of course, I'm also perfectly happy to see this box go away if it isn't supported.