title: Way in Firefox to show current window dimensions?
body: <p>Is there any way in Firefox to show the dimensions of the current viewport? Ideally in the status bar and updating "live" as you resize the window, as this would be extremely useful for responsive layout testing!</p>
  
  <p>I've used "MeasureIt" but that requires you to draw with a ruler, which is tedious and quite possibly inaccurate depending on the ability and mouse resolution of the user.</p>