C#浮动的窗口如何实现？

public class Win32API

{

[System.Runtime.InteropServices.DllImport("user32.dll")]

public static extern bool PtInRect(ref Rectangle r, Point p);

}

/// <summary>

/// 停靠到顶端

/// </summary>

private void BerthTop(object sender, EventArgs e)

{

System.Drawing.Point pp = new Point(Cursor.Position.X, Cursor.Position.Y);

Rectangle Rects = new Rectangle(this.Left, this.Top, this.Left + this.Width, this.Top + this.Height);

if ((this.Top < 0) && Win32API.PtInRect(ref Rects, pp))

{

this.Top = 0;

}

else if ((this.Top > -5) && (this.Top < 5) && !(Win32API.PtInRect(ref Rects, pp)))

{

this.Top = 5 - this.Height;

}

}

private void setTouMing()

{

frmSetOpaticy opa = new frmSetOpaticy(this);

opa.StartPosition = FormStartPosition.CenterScreen;

opa.ShowDialog(this);

}

//private void timer1_Tick(object sender, EventArgs e)

//{

// System.Drawing.Point pp = new Point(Cursor.Position.X, Cursor.Position.Y);//获取鼠标在屏幕的坐标点

// Rectangle Rects = new Rectangle(this.Left, this.Top, this.Left + this.Width, this.Top + this.Height);//存储当前窗体在屏幕的所在区域

// if ((this.Top < 0) && Win32API.PtInRect(ref Rects, pp))//当鼠标在当前窗体内，并且窗体的Top属性小于0

// this.Top = 0; //设置窗体的Top属性为0,就是将窗口上边沿紧靠顶部

// else if (this.Top > -5 && this.Top < 5 && !(Win32API.PtInRect(ref Rects, pp)))//当窗体的上边框与屏幕的顶端的距离小于5时

// this.Top = 5 - this.Height;//将QQ窗体隐藏到屏幕的顶端

//}