Is there a way to get Inkscape to tell Windows how to create thumbnails of SVG documents? I've already got this (specifically the third one) but it doesn't support some of Inkscape's extensions (like blur) and it doesn't handle self-intersecting objects well.

That's all there is, afaik. There's the Adobe SVG Viewer, which is no longer supported by Adobe (or anyone). You could still use it, but I don't think it does the thumbnails.

But my view is that Renesis is better than nothing, even though it's not perfect

Hello,

to view Thumbs in Windows XP/Seven use --- Windows Thumbnail Plugin --- http://www.examotion.com/index.php?id=p ... nload&L=11

Work fine and fast.