How did you tweak it the first time? Is it always the same folder you want this for? (I'm assuming that this folder, if there's only one, already opens as thumbnails outside of Thunderbird, but that is the default for folders of pictures.)

If I could remember the tweak, OR, I wouldn't be asking the question.

It's not always the same folder, but it's always an image folder that opens everywhere else in Windows by default in thumbnails not list view.

But maybe you remember something about it--e.g. that you found it on the web, or that you found it when looking for something else.

I don't run thunderbird (I'm a gmail person who browses in Opera) so I can't try things here, but I wonder what would happen if you ignored the fact that images were the default and changed those directories to display as images as if they weren't already doing so. I also wonder if other applications have this same problem. E.g. if you do an "open" or "save as" from Word into an image directory, I'll bet it doesn't show it as images.

OR, a file opened in Word to insert an image opens as thumbnails. It's only a T-bird issue, in every other application, the default view is thumbnails.

As I said in my question to AskMe, I did find something on the web way back which fixed this, but I can't find it now and didn't bookmark the link. I've looked, believe me, I've looked.

Maybe ImageFox will do it.

The answer turns out to be a little bit of freeware - OpenWide - which I'd had on my previous install and had forgotten to transfer.

It wasn't a T-bird issue at all, but a Windows one which this software fixes. Now when going to the Open/Save dialogue box, it'll open in Thumbnails instead of list view.