function aboutMessage(event) {
    var pos = mousePosition(event);
    aboutMsg.style.left = pos.x + 'px';
    aboutMsg.style.top = pos.y + 'px';
    clearTimeout(aboutMessage.t1);
    clearTimeout(aboutMessage.t2);
    aboutMsg.style.display = 'block';
    aboutMsg.style.opacity = 1;
    aboutMessage.t1 = setTimeout(function() {aboutMsg.style.opacity = 0;}, 2000);
    aboutMessage.t2 = setTimeout(function() {aboutMsg.style.display = 'none';}, 2500);
    event.preventDefault();
}