Any insight into opening external links in a new tab would be greatly appreciated as it greatly improves the user experience by leaving the user on her page while perusing external content.
I'm not aware of a way to make an InDesign hyperlink or button open a new tab in Web Viewer. The "Open in Device Browser" option in the Overlays panel has no effect in Web Viewer. I think you need to use HTML.
I definitely understand how this works when creating content with HTML, but is there a corollary for authoring fixed-width layouts in inDesign CC? I have a feeling that the URL field in the hyperlink panel in inDesign cannot take the target=_blank command. Is "open in a new tab" only available for HTML content?