C# 退出提示 事件提示两次问题

 

private void frmCtiState_FormClosing(object sender, FormClosingEventArgs e)

{
     if (e.CloseReason == CloseReason.ApplicationExitCall)
         return;

     DialogResult result = MessageBox.Show("是否退出系统?", "消息", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
     if (result == DialogResult.No)
     {
         e.Cancel = true;
         return;
     }
     else
     {
         e.Cancel = false;
         Application.Exit();
     }