This widget displays the list of instruments in the song, you can scroll through the list with the mouse wheel or other scroll gesture. The list is designed designed to keep the current instrument in the center of the list, the list scrolls through the current marker, shown as a grey border. Each instrument is numbered, with the current instrument shown in green.
Each instrument has a name, a single click with the mouse will select the instrument, moving it immediately to the centre of the list. Double clicking on the name will switch to text edit mode, allowing in-place editing of the instrument name.
The current instrument is key in other aspects of song editing, for example, when using the virtual keyboard to play sounds, either interactively or when entering notes into a pattern, the currently selected instrument is played or entered into the pattern.
The toolbar in this widget has a single button, to create a new instrument. When adding a new instrument, it will be automatically added to the end of the list, given a reasonable default name, and selected as the current instrument.