Or rather "xray unselected". From being use to work in maya, this is something I really miss (tho maya is a xray all command). When modelling its anoying having to select another object in order to xray it. Ofcause you can just turn to wireframe, but it would be nice if I could xray all except the object im working on (as a toggle).
I acually found a script doing this, but cannot get it to install correctly (xrayOthers). I can run the .mse, but it will only apply the xray, not toggle back.
Since its .mse, I dont know how this is done in the first place.