Slur from a note/chord to a rest should be hoizontal
In order to describe more precisely a "laissez-vibrer" or a "let ring" a common notation is to tie the note to a rest. It is more explicit to what is expected from the player.
In MuseScore, this implies using multiple voices, hiding the tied note, ...
It would be nice if a chord could be tied to rest without having to do all those manipulations.