1.首先，窗体的FormBorderStyle设置成None,不要控制边框。

2.然后，TransparencyKey和BackColor颜色设置成相同的,这样,窗体就透明了。

3.最后，窗体的拖动

private void pictureBox1_MouseMove(object sender, MouseEventArgs e){     if (e.Button == MouseButtons.Left)     {          this.Left += e.Location.X - this.oldX;          //新的鼠标位置                       this.Top += e.Location.Y - this.oldY;      }}  private int oldX = 0;        private int oldY = 0;        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)        {                 if (e.Button == MouseButtons.Left)                 {                          this.oldX = e.Location.X;                  //鼠标原来位置                       this.oldY = e.Location.Y;                  }        }