DC provides this capability, placed components will become de-highlighted. Unfortunately I don't have DC installed on my machine currently so cannot provide details of where this is defined, though I think it is automatic if you use the Place from Schematic (or similar option) in Place mode.
One addendum - this functionality appears to have stopped working in VX.1, we are investigating the reasons why.
Thanks for the reply.
I am an EE learning to do PCB design in my spare time, hence the rather simplistic question.
So if the feature is no longer working I have to wonder how PCB designers keep track of the schematic components they have placed into their PCB layout. I'm considering printing out the schematic and using a red pencil to cross off each device I've placed...seems rather crude, but effective.
You can use the Component Explorer in Xpedition to see which parts are not yet placed.
I am also new to design Capture and want to learn more about it for my future projects. I don't know much about it but as per my observation in the Design Capture you can de-highlight the placed components.
It is automatic but you have to use the Place mode.