может так.
pic - твоя панорама
лежит по у от 0 до pic._height

Код:
stop();
shirina_ecrana = 550;
pic.onEnterFrame = function() {
if (_ymouse>0 && _ymouse<=this._height) {
if (_xmouse<shirina_ecrana/2 && this._x<0) {
this._x += 1+(shirina_ecrana/2-_xmouse)/10;
} else if (_xmouse>shirina_ecrana/2 && this._x>shirina_ecrana-this._width) {
this._x += -1-(_xmouse-shirina_ecrana/2)/10;
}
} else if (_ymouse>this._height) {
this._x += shag;
if (this._x<=shirina_ecrana-this._width) {
shag = 1;
} else if (this._x>=0) {
shag = -1;
}
}
};