I honestly don't think there is a setting for that, unfortunately, but I fully understand and sympathize with your reasoning. Sometimes I find myself pressed for time between IRL stuffs, but want to peek in on the Market Board or what have you for a brief moment, for example. A moment that can easily be derailed by everyone engaging me the moment I log in, and often times I end up not accomplishing what I originally logged in to do so as not to appear rude.