Arpeggios and chords across clefs.
Arpeggios across clefs are some of the most common features in music, especially in the Romantic period. However, it seems I can't do that directly on Musescore. As a result, every time I want to make these, I need to extend two separate arpeggio lines to merge them and edit the notes manually on the pianoroll editor. This can be frustrating if I need to do these for hundreds of time in a single piece. The following picture demonstrates what I meant by arpeggios across clefs.
Similarly, despite being a common feature, I couldn't create chords across barlines either. This will be a convenient feature if there are a lot of chords in the middle registers as we no longer need to utilize a lot of ledger lines below the treble clef/above the bass clef. The following picture is an example of chords across clef in Liszt's Transcendental Etudes No.2