If I remember correctly, only A, AREA, BUTTON, INPUT, LABEL, SELECT, TEXTAREA create focus/blur events. If you want to hide the popup by clicking outside it, you have to for example listen to click events on document and check if the event occured inside or outside the popup.
Sample code:
$(document).click(function(e){
if($(e.target).is('#MainCanvas, #MainCanvas *'))return;
$('#MainCanvas').hide();
});