Do not override existing channels when changing fixtures (or only when confirming)

[bjdmeest]

Assume you have 3 rgb fixtures (so channels 1-3, 4-6, 7-9), and you change fixture 1 to a single channel, I would expect this to result in 3 channels, otherwise you end up with channels 1, 2-4,5-7, actively impacting all existing cues. You could repatch, but if you have 30+ fixtures this is a pity. Is there a straightforward way to implement this feature? I'm happy to discuss and see if I can contribute