var xs:int = 5;
var ys:int = 6;
addEventListener(Event.ENTER_FRAME,xq1);
function xq1(e)
{
if (xq.y - xq.height / 2 <= 0 || xq.y + xq.height / 2 >= 400)
{
ys = - ys;
}
if (xq.x - xq.width / 2 <= 0 || xq.x + xq.width / 2 >= 550)
{
xs = - xs;
}
xq.y -= ys;//xq元件
xq.x -= xs;
}