If I add a layer (map service) to a map, then show the map contents, then click the layer and open its description, the description opens in the same browser tab as the map (Firefox 4). It should open in a new tab or window because you can't go back to where you were. When you click the Go Back button in the browser, you lose any changes you had made to the map, such as having zoomed in to a location. And there's no warning -- nothing that says "save the map before you look at the description." (Which you shouldn't have to do in my opinion.) Thanks,
Tim