Center a popup window

programming flash
1

Hi, I’m using this code but the x and y is not working for me. The window goes to top-left of screen automatically. Is possible to center the window to the whole screen?

this.onPress = function(){ 
    this._parent.attachMovie("mypopmc2", "window", 999);
    window._x = 250;
    window._y = 150;
}