function crossBrowserEventListener(target, trigger, functionPointer, bubble){
	//default action leaves default behaviour unchanged
	if(typeof(bubble) === "undefined")
		var bubble= false;
	if(typeof(target.addEventListener) !== "undefined"){
		target.addEventListener(trigger, functionPointer, bubble);
	}
	else{
		target.attachEvent("on"+trigger, functionPointer);
	}
}

function preventDefaultAction(evt) {
	if (evt) {
		if (typeof evt.preventDefault!== 'undefined') {
			evt.preventDefault(); // W3C
		} else {
			evt.returnValue = false; // IE
		}
	}
	// safety for handling DOM Level 0
	return false;

}