Selection bug - lots of red edge lines of whatever mouse cursors over

I'm not 100% sure how I am triggering this bug, best I can tell is I am working with toggling sub-d with the tilde/backtick key (`) and doing viewport camera rotation with [ALT].
I haven't been able to figure out what combination and what exact action though.

What happens though is moving the mouse across the viewport it looks as though I am making edge selections, though the manipulator panel down the bottom does not show an increase in selection number, so I think it may be visual only.

I have also tried to switch sub-object selection mode (edge, faces, vertices) and the issue persists when I get back to edges.

Restarting NVIL seems to be the only way to get rid of the bug.

I have re-opened my scene file after the bug and it does not seem to effect my scene file.

Best regards.

Which version were you using?

I tested this morning on the current steam version and wasn't able to trigger it.
I will update if it comes back.