Solved:
A shortest scrollbar click detection I could come up with, tested on IE, Firefox, Chrome.
var clickedOnScrollbar = function(mouseX){
if( $(window).outerWidth() <= mouseX ){
return true;
}
}
$(document).mousedown(function(e){
if( clickedOnScrollbar(e.clientX) ){
alert("clicked on scrollbar");
}
});
Working example:
https://jsfiddle.net/s6mho19z/