The BIM Viewer is good, but because we can only open one document/drawing at a time in the Viewer it limits its use. Most people have 2 screens these days, possibly even more, so adding the ability to open the BIM Viewer in a new browser window would be great, so that multiple drawings/documents can be viewed/annotated/marked-up etc at the same time.

The best case scenario for this is still this Idea that was added a while ago: - HERE, which involved adding tabs along the top of the BIM Viewer.