I've been having an issue a couple of times: I send out some fabbers to build a number of mex in places all over. Some time passes and I don't see those fabbers around, presumably they were shot down by the enemy. I decide to send out some different fabbers to build mex in one of those areas, when I do the white blueprints for the original mex are still around and these stop me from adding a different set. So I end up with a bunch of metal spots I can't queue up new extractors for, a set of blueprints which I can't identify any surviving fabricators being responsible for, and trouble with my economy. A few things would be useful in the interface. Like being able to identify the fabricator(s) some blueprints are assigned to. And being able to build over top of other blueprints (at least as far as mex goes) so you can have a set of fabbers usurp the mex that another group was going to build. The ability to delete specific blueprints (ideally being able to mass select and delete). And perhaps even the ability to use the "assist" command to force a fabber to build a specifc structure that was supposed to be queued up for a different fabber to build "later".
Normally when you see the white blueprint the fabber is still alive and stuck somewhere or still building somewhere else and those mex are end of queue. Either way if you use area build for mex the new fabber will build over the white blueprint. To area command build (if you don't know) select the mex, drag click an area where you want the fabber to build mex and release the mouse button.
