Making chord symbols belong to the system, not to a staff

I think this has been discussed before and I wonder if there is a solution to it.

If you have a score with a vocal staff and a guitar staff + tab staff, then you would add the chord symbols to the vocal staff. But when the score goes to a guitar solo, you would like to hide the vocal staff to save space. In that case you may like the chords to still show, even if you have selected to hide empty staves.

The solution would be to be able to make the chord symbols "system chord symbols" so that they would still show on top of the topmost staff. The only way I can currently figure out is to attach the chord symbols to the guitar staff when there are no notes in the vocal staff, or to not use "hide empty staves" at all.

I realize this is not a topic for all sorts of instrumentation, but vocals + guitar + chords is common enough I think. Is there a way to do it in MS4?