I just want the picture frame (with border) and be able to see part of
the desktop background in it, I can achieve this by creating a
transparent image, and using that image as the image in the Picture
Frame. Can there be an option just to have no image as the image
(which would be essentially equivalent to having a transparent image)?

As far as I can tell, unless you "fake it" like you suggested, there isn't an option to do like you suggested.

I tried sending an email to the email address in the Picture Frame widget, plasma-devel@kde.org but it bounced.

The address plasma-devel@kde.org is valid, which bounce message did you get?

bcooksley wrote:The address plasma-devel@kde.org is valid, which bounce message did you get?

Mail has been rejected as SPAM [BODY]

Please accept my apologies for that, it most definitely should not occur.
Can you please post the full content (including headers) somewhere such as Dropbox, and paste a link to it here?

Sorry, we were unable to deliver your message to the following address.

<plasma-devel@kde.org>:
Remote host said: Mail has been rejected as SPAM [BODY]

--- Below this line is a copy of the message.

I just want the picture frame (with border) and be able to see part of

the desktop background in it, I can achieve this by creating a
transparent image, and using that image as the image in the Picture
Frame. Can there be an option just to have no image as the image
(which would be essentially equivalent to having a transparent image)?

- Enda

Thanks for that information. Your message should be accepted now.