Oh, Thank You so much, Birthe! - It works beautifully :) I just knew there had to be some simple mechanism for doing this. I'd read a few posts about using _canonical_uri under TWC in other situations, but never thought about trying it for this...
I've now whipped up a SideBar tab using your method, some code from the Hello There tiddler <http://tiddlywiki.com/#HelloThere> on the main TW site, and Tobias Beer's Link Images Plugin <http://tobibeer.github.io/tb5/#Link%20Images>. It still needs some tweaking to get it exactly like I want it, but thanks to you, I'm well on my way :) So, do you have any ideas on how I could accomplish my other wish, of having the background change whenever a tiddler is opened? I'm thinking that some form of the above method might just work. Maybe with the LinkCatcherWidget. Back to the laboratory for more experiments... --Zaphod On Tuesday, July 26, 2016 at 3:56:51 PM UTC-4, Birthe C wrote: > > Create a tiddler for the image. Give the type and create the field > _canonical_uri, put your external link in this field. Save the tiddler. Now > you are able to select your image in $:/ControlPanel/Theme Tweaks - Page > background image: > > > Birthe > -- You received this message because you are subscribed to the Google Groups "TiddlyWiki" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/tiddlywiki. To view this discussion on the web visit https://groups.google.com/d/msgid/tiddlywiki/e79c1ce9-50fb-48a5-a9cf-4063947a4dc6%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.

