This might be a bit harder but it might be worth it. Several editors have this functionality and it's similar to entering notes in the PRV. When you click to enter a new note, then drag the mouse to the right, the note duration is extended. This allows one to create longer note durations without changing the current duration setting. Might want to implement drag left note duration shortening as well. Note that this might interfere somewhat with the current behavior where the note position is modified, an alternative might be to use a modifier key like Ctrl+Click or Alt+Click.