Don't use the mouse! Use the keyboard!
Don't be surprised if the sound lags dramatically behind your fingers!
Press Shift key for an octave higher, Ctrl key for an octave lower.
Only eight oscillators are available, but roll-over characteristics of your
keyboard will probably prevent you from playing that many notes simultaneously.
(On some keyboards, you might not be able to play more than three.)
If notes get "stuck," press the ESC key.