SilverLight Out of Browser 下获取屏幕的分辨率

if (!content.IsFullScreen)//IsFullScreen==false
            {
                dispatcher.BeginInvoke(() =>
                {
                    //switch to full screen 在全屏的模式下获取，如果是多屏时，他会获取主屏幕的分辨率
                    content.IsFullScreen = true;
                    this.ConfigRoot.Width = (int)Math.Round(content.ActualWidth);
                    this.ConfigRoot.Height = (int)Math.Round(content.ActualHeight);
                    //switch back to windowed mode
                    content.IsFullScreen = false;
                    //send the results
                });
            }