Sxx shouldn't have anything to do with other effect commands.

Moving on, I have a feature request.

There is a "remove unused patterns" command, but in the next release, I'd like to see a "remove duplicate patterns" command. It can get hard keeping track of what patterns you've made and what you need to make a new one for, so being able to have the program scan for duplicate patterns and replace them with the original would be useful to reduce clutter.

Here's a bit of audio driver trivia for you. If you listen carefully to some of the longer notes with vibrato you can sometimes hear a little bit of cyclic clicking. This was a side-effect of the way I programmed the vibrato. On the APU, writing to the register that has the upper 3 bits of the frequency setting causes an audible click. This is because if you are using the hardware envelopes/timers, it's this register you write to to initialise the envelope/timer (I actually don't use the hardware envelopes or timers).This is not so bad at the start of a note where it's hardly noticed but because the APU is being written to every frame in my audio driver, I would only write this register when absolutely necessary. Therefore, because the vibrato programming is making small cyclic adjustments to the lower 8 bits of the frequency setting, most of the time it's not necessary to write the upper 3 bits. However, if when you add a value to the lower 8 bits it causes an overflow and therefore a requirement to increment/decrement the upper 3 bits, it meant that the upper 3 bits register had to be written, causing a cyclic click in the voice output. Normally I'd get around it by transposing the whole track up/down a semi-tone or two until I was lucky enough not to have any long notes that exhibited this side-effect. I didn't always spot them, as you can now hear. If you listen closely.