You should be able to set a min-max limit on the "multiple input" feature on custom blocks. If the min limit is set to 2, the multiple input will start with 2 inputs and there won't be a back arrow. If the max is set to 5, once it reaches a total of 5 inputs, the forward arrow would disappear.
I don't see any use for this, well, I see a use for the min limit, but not the max.
If you set the max to 1 then what you have is an optional input. And you should be able to give it a default value in that case.
But there should be three numbers specified: min/default/max. The default is the number of input slots in the block in the palette. Good for things like append or join, with two inputs by default. That's probably what you're thinking of using min for, but there are independent reasons for min: think of an AVERAGE block which is going to divide by the number of inputs. It should have min=1.
that makes sense.
Support
Hey I like this feature! I remember in the MAP block the max is 3, with default names "value", "index" and "list?
Yes, we have the feature for primitives, just not (so far) for custom blocks.
I do hope we can have this feature soon!