In the note pattern editor, you can click and drag horizontally on a note to adjust its duration.
N: set pattern to the lowest-numbered one not used anywhere in the song (This can help you find gaps in patterns that you missed).H: move playhead to the selected bar ( Here).F: move playhead to the First bar in the song.Shift & Drag: select part of a pattern (long press on touch screen).
When JummBox has focus (click on its interface above), you can use these keyboard shortcuts: