Missing vital Octave interval in songbook transposing!

While transposing the key it may easily happen that note's become written 4 extra lines below (see fig.1) or above (sse fig.2) the standard 5 line bar which for many people reads difficult. Usually you need to transpose the notes one octave higher respectively lower. A vital function for the songbook is an "octave interval up and down function" to be added asap.