275 votesdnatic09 commented
I think it should just open the MightyText web application. If you use PowerView by default, it should move that conversation into the view and give "focus" to it. If you use classic, it should snap to that conversation in classic mode.
Do not pop up an additional chrome/browser window. I like leaving the mighty text tab open 24/7. Every time I get a text, a new window is opened for no reason when I already have the tab open.