in microb enter: about:config into the URL box, and go... Create those two keys as booleans make their values false close microb, and then launch it again. Should be good to go.
i know what you mean, the microb gui is not exactly intuitive for this. what i did was close all microb windows and open x-terminal. then $ killall browser $ find . -name prefs.js make a back-up copy of prefs.js, just in case edit prefs.js to insert the two lines save prefs.js open microb, look at about:config to make sure the two directives have been recognized correctly