Better UX for dragging vertices through interchangers?

[kram1032]

In a situation like this:

I find it very hard to figure out how to manipulate the wires to get the vertex to move up or down. The situation is even worse when a vertex is on the other wire, "behind" the crossing.

1. Would it be possible to make vertices behind crossings still visible?
2. Would it be possible to get diagonal drags / gestures to move the vertex up or down without weird counterintuitive wire manipulations?

This used to be a non-issue in Globular, as degenerate states like this were disallowed, but now it's pretty annoying to randomly click around the wires until it happens to do the right thing.
-- I understand that there are clear rules being followed here, but as it stands they are really difficult to figure out.

Some sort of telegraphing (move preview on hover? - not sure how to do something similar for tablet users) would also help a lot, just so you understand what your options are at that particular moment.