Selection, action

LMB-drag always selects a span. LMB-click just defines a start, a span without length. It could be like placing a cursor in text-editing. The span itself should be visualized. Overlapping notes are selected. There could be a command to reduce the selection to notes that are entirely within the span. If a span is empty and in a single row, it should be turned into a note automaticaly. * Ctrl-LMB: add span * Shift-LMB: edit existing spans * Alt/Meta-LMB: move span * F: fill in note(s). If the span is more than 1 row high, a chord menu could appear [Return key comes to mind, but is in use for "Playhead to Edit"] * Del/Backspace: delete The following actions either work by holding down the key, stopping by releasing it, or pressing the key short and terminating with a click: * M: move * A: move note_on * Z: move note_off * V: adjust velocity