Make the "Use this browser..." interface clearer
When setting up a rule, if the resulting action ends in "...", the interface does not make clear what the user should do to finish the setup process. The simplest way to make the interface clearer would probably be to change the text on the "Change" button to something like "Pick" or "Choose", and perhaps use a placeholder with text like "No browser chosen" where the browser icon and browser name would be once a browser has been chosen.
If you were to redesign the interface a little bit more, it might make sense to make the entire area below the action dropdown be clickable, rather than just the "Change" button, so that the user could click the browser name or placeholder text to get the "Change" menu.
Excellent feedback, thanks!