private void zoomOut() {
		int lgth=timeLineObject.displayEnd-timeLineObject.displayStart;
		timeLineObject.displayStart-=(lgth/2);
		timeLineObject.displayEnd+=(lgth/2);
		if (timeLineObject.displayStart<0) {
			timeLineObject.displayStart = 0;
		} 
		if (timeLineObject.displayEnd >= timeLineObject.timeLineLength) {
			timeLineObject.displayEnd = timeLineObject.timeLineLength;
		}
	}