If you add an External URL as an item in a Module, and the site/page you are attempting to add does not allow iFraming, users will get a message with a sad face and a "refused to connect" message. If they click on the link at the top of the screen, the webpage will open in a new Tab. So, one may as well Edit the External URL item to "Load in new tab" since either way, it requires two clicks. It would be nice if the "refused to connect" message would say, "click the link above" since not everyone will notice that link and work around.
Interestingly, Canvas Guides are such pages that don't allow iFraming.
Can this be made easier for the person designing the course and users?
(I did contact Canvas Help and was told to submit as feature idea)