How do I re-register or enforce stl-thumb as the default .STL thumbnail generator in Windows?

[Xuis]

How do I re-register or enforce stl-thumb as the default .STL thumbnail generator in Windows?

I installed F3D to have thumbnail previews for .STEP files, and it also grabbed control over .STL thumbnail generation.
I would like stl-thumb to generate my .STL thumbnails because it generates more visually attractive thumbnails. However, I would still like F3D to generate .STEP file previews on my machine because that is the only application I know of that has that capability.

• I have uninstalled and reinstalled stl-thumb in hopes that it would grab control back from F3D, but no luck.
• I have uninstalled F3D, and .STL thumbnail generation now works properly through stl-thumb, but I do not have .STEP file thumbnail generation.
• I uninstalled and reinstalled F3D and uncheck the box that registers it as a thumbnail handler, and it now does not generate .STL or .STEP file thumbnails.

Is there a way I can tell Windows to generate .STL files through stl-thumb, and .STEP files through F3D?

To avoid confusion, I am not trying to change the application that "opens" the .stl, just the application that generates the windows preview thumbnail for the .stl.

Thanks for writing this great piece of software! It has helped me every day since installing it.