function swap_menue(caller) {
			callerSource = caller.src;

			if(callerSource.indexOf('_over') >= 0) {
				caller.src = callerSource.replace('_over','');
			}
			else {
				splitPoint = callerSource.lastIndexOf('.');
				caller.src = callerSource.substr(0,splitPoint) + '_over' + callerSource.substr(splitPoint);
			}
		}