As noted above:

Or, if you want WinSCP to open the files in application associated with their extension, set Operation to perform on double-click to Open:
https://winscp.net/eng/docs/ui_pref_panels

Maybe we are misunderstanding one another.

I am talking about clicking on a file inside WinSCP on the remote side. Specifically, an image (or perhaps a PDF). By default, out of the box, without any configuration, WinSCP is bringing up such files in the text editor which is not very useful to anyone.

However, if I manually configure the windows Photo viewer for jpg and png (and other file types), then, when I open those remote images, WinSCP does the expected thing, it downloads (I guess temporarily somewhere) the file and opens it in the Photos app to look at, and the temp file goes away after it's closed.

All I am saying is that instead of a user having to manually configure it to do something for those file types, maybe you could configure a few of these useful popular file types on installing WinSCP. To be clear, I am talking about WinSCP's configuration, not Windows. Or maybe not even configure it but somehow use Window's default to open files that WinSCP doesn't have a specific rule for.

It's entirely possible that WinSCP is supposed to do this but it did not do it for me. Maybe there is a setting I have set wrong? I have been using it for many many years and never really noticed it do that so it's not impossible that there's something old on my machine and a new fresh install would act differently. I admit that I did not try that!

What about adding the default windows photo display tool as the default image display tool to that list? Seems like that would be reasonable anyway. I can't see any reason a normal user would ever want to open an image file and look at it in text.

I would say same for pdf and html files too would be reasonable. Perhaps other formats too.

Oh geez, I did not realize that list was ordered! I completely missed the up/down buttons!

Maybe you should by default insert new rules above rather than at the end? Or maybe a friendly note in bold noting that the *.* should be at the bottom as a catch-all?

Thanks for the quick response!

https://winscp.net/eng/docs/ui_pref_editor
Maybe you didn't put your jpg/png rule above the *.* internal editor rule.

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Or, if you want WinSCP to open the files in application associated with their extension, set Operation to perform on double-click to Open:
https://winscp.net/eng/docs/ui_pref_panels

I tried to set an external viewer for jpg and png files but it just opens them in the internal text editor. A reasonable default is to use Windows' system default which is the Photos app on Windows to display an image. You could use it for the many other times of images as well. Similar if you were going to try and open a movie file.

What I ended up doing was just download the directory and double clicking files to open them but this becomes inconvenient when there are a lot of files and you might end up having to download individual files and then click on them, in 2 steps as opposed to one.