As a shameless hack: put a layer on top, fill it with the color you like the most and that will prevent the document from revealing what's going on below.
It's a bit like hiding the dust under the carpet, there might be cases when you need to turn it off (e.g. merge on top) but for basic stuff it does the job.
Besides that, there's a undocumented "viewless document" or something like that, but you can do very limited processing - XBytor wrote something on ps-scripts.com years ago.
Best
Davide Barranca
www.davidebarranca.com
www.cs-extensions.com