Cross-staff notation across non-adjacent staves
I've been engraving some early-mid 20th century piano scores by French and Italian composers who have some passages with additional staves to separate voices.
I have some cases where there is cross-staff notation from the top treble staff that needs to go to the bass staff, but it appears I can only get "half way" to the intervening lower treble staff.
In the example below, I can't do the yellow moves, but the up+down moves marked in orange are fine. 
In this case I've worked around by situating that voice in the middle stave and pushing up/down. However I have some 4 staff scores where this doesn't work.
There are also cases where I have started the score with two staves having cross-staff notation, and subsequently added an additional staff. In these cases, Musescore now shifts the cross-staff notes into the wrong staff. When I use the style settings to hide the empty staves, it thinks these staves are NOT empty, and so I have to re-do all the measures with cross-staff notation. 
This measure was relatively easy one to fix but many measures had a lot of position-sensitive notation with tuplets and serpentine slurs that are horrible to interpolate with additional in-staff voices.
In any case, the feature needs a sense of moving notes to a fixed rather than relative staff.
Comments
Put the notes into the middle staff and cross staff from there to above and below
In reply to Put the notes into the… by Jojo-Schmitz
As noted in the text above that only works in a few instances.
Where the score only has two staves showing, and the cross notation is between the outer staves the middle staff cannot be hidden if the notes live there.
I've tried moving notes wholly from one staff to another but any connecting slurs from other measures break the staff hiding.
In reply to As noted in the text above… by memeweaver
Ah, indeed when the middle staff is hidden that won't work