1. how do you kickstart the thumbnail display for a particular version? i.e my NX12 history shows thumbnails but file - open does not. NX 10 shows no thumbnails in either place.
2. is it possible to show thumbnails in multiple releases at the same time? i.e. I have read referernces to a shell dll to fix in individual releases, but evidently the root changes from 10 to 11. I am currently running 10, 11 and 12 at any given time, bouncing back and forth.
Unfortunately this affects all of the thumbnails in the resource library as well. I currently need to demo a symbol library in 10, which is difficult with no thumbnails.
I am not sure I fully understand the problem you are trying to address. Thumbnail previews are stored within each part file. In NX 10, you will be able to see those previews in the History palette of the resource bar and the preview window within the file-open dialog but nowhere else. From NX 11, the previews appear everywhere NX interacts with parts such as changing displayed parts, or changing windows, etc.
Now, having said that, NX parts saved in NX 12 cannot be opened in earlier versions. That also means that the thumbnail previews saved within those parts will not be visible in earlier versions either since those earlier versions will not be able to access the thumbnail information.