Hi DesuDeus, something like flashing or a really striking color like red would probably be really distracting in regular operation. Like for example if you're working on a box in the 3D view it would look pretty weird in that case if the hidden lines were pulsating at you.

What about if there was a mode you could turn on where only the hidden edges of just the selected objects were displayed at all, would that solve this problem for you?

- Michael