Wonderful! Thanks very much indeed! This makes all the difference! :-)
If you're wondering why I care… when using an emulator on a modern keyboard, the right-hand Shift key is perfect for 'jump'. I typically choose either Q, W, Shift (JSW-style) or Z, X, Shift. I don't like using the space bar for 'jump' as it's too big and clumsy, but a regular key like M is too small for a one-handed function. The right-hand Shift key is just perfect.