Prototype settings to show fluid arrows on overlay

[GotLag]

I'm told that currently, whether or not an entity shows fluid in/out arrows on the Alt overlay is set internally on a per-entity-type basis. Could this be changed to be defined in the entity prototype, on a per-fluidbox (or better yet, per-connection) level?

For example, my mod Flow Control adds several types of one-way valve, but as they're all based on storage tanks they show no directional flow indicators. If I could force the output-only connection to show an arrow it would be much easier for users to see how it works and which way it's pointing.