My biggest pet peeve with the pattern editor is, when working on a multi-step drum beat, it doesn't show any kind of clear boundary/divider between the steps.
So, my idea is to make it do that. Image attached depicting a rough mockup of what I'm talking about (in 13/8 time signature, partly to demonstrate why the lack of a divider is annoying).
I can't imagine this would be too hard to implement, if somebody were so inclined.