http://topic.csdn.net/u/20101123/17/c9e9e15e-4002-4619-9e17-9da387269b51.html
privatevoid lab_exit_MouseEnter(object sender, EventArgs e)
{
this.lab_exit.Image = Image.FromFile(path+"\\icon\\关闭-2.png");
}
privatevoid lab_exit_MouseLeave(object sender, EventArgs e)
{
this.lab_exit.Image = Image.FromFile(path+"\\icon\\关闭-1.png");
}