In Firefox, when in scratchpad and working in Environment > Browser, if do alert, it alerts in the window behind it, to make the alert happen within the scratchpad window use this technique.

_scratchpad-AlertWithinScratchpad

var spwin = Services.wm.getMostRecentWindow(null); //this gets the scratchpad window
var str = 'rawr';
var str = str[0].toUpperCase() + str.substr(1);
spwin.alert(str) // will upper case str this is just to demo the alert comes in the scratchpad window