A while ago I worked out I could put an XPage in a sidebar panel. I had also created a widget to act on Live Text (a person's name or email address) to launch the relevant contact in our CRM application, Touchpoint. Then I had a project where I wanted to be able to act on Live Text to launch an XPage. Furthermore, the application did not have Anonymous access, but I didn't want the user to have to log in each time. It actually proved to be quite easy - it took about half a day of investigation. If you've never tried it, it's worth looking at the video embedded here. Hopefully it will give you a head start on doing something similar and expand your horizons for acting on Live Text, automatically logging into an authenticated application from a widget, linking to an XPage from a widget, and editing the raw XML to modify your widget.
I'd like to make two points here. Firstly, because we're opening the XPage in a browser, this will work with 8.0.x Notes clients. All you need is an 8.5.x server for your application. (I've tested this with 8.5.1 server and 8.0.2 client, because that's my customer requirement.)
Secondly, I've found it a bit frustrating that if you link a widget action to launch in a sidebar panel, it creates a new sidebar panel each time. For a developer, that's not a problem. When I get a load of windows there, I close them. But you can't expect end users to always do that, and so sooner or later they'll stop using the sidebar. If anyone knows how to launch in the existing sidebar panel, it would be great. I haven't gone into detail on editing the XML files produced by widgets, but couldn't see anything obvious. Equally, if you know it's not possible, it would be good just to have confirmation.
So here's the video (if it doesn't default to 720p, change it to that to ensure best resolution) :