I'm doing some freelance work with a real estate agent who sends me pictures of vacant properties and I add virtual furniture to the various rooms.  The attached image is an example of what I am doing and also illustrates the reason for my question in this thread.  

The original photograph shows a mirror on the wardrobe door.  When the virtual furniture is added with the Blender world colour set to the rooms paint colour the reflection that I get in the mirror matches the colour tone of the room but the reflected details of the actual room in the original photo are gone in the overlay.  Having a transparent world colour in Blenders reflection renderlayer would save alot of editing and manipulation of the Blender render in Photoshop.

My Renderosity Store
Virtual Furnishing
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