Exactly this is the problem with grafting visual programming interfaces onto textual programming semantics. One of the main important reasons to do VP is to be able to inspect the code, to easier see what it does, ideally at a glance. Yet as you point out, simple recursion can make this really difficult to do. My thesis is that we need VPLs that have semantics specifically tailored for the visual interface. It's possible, but takes a bit of thinking to work out