create and destory MFC modeless dialog

new and create

void CProgramDlg::OnBnClickedButton1()
{
CDlgModeless * dlg = new CDlgModeless();
dlg->Create(CDlgModeless::IDD, this);
dlg->ShowWindow(SW_SHOW);
}

需要处理，non-client area destory 消息，OK 按钮，Cancel 按钮

BEGIN_MESSAGE_MAP(CDlgModeless, CDialog)
ON_WM_NCDESTROY()
ON_BN_CLICKED(IDOK, &CDlgModeless::OnBnClickedOk)
ON_BN_CLICKED(IDCANCEL, &CDlgModeless::OnBnClickedCancel)
END_MESSAGE_MAP()

在 non-client area destroy 时，delete 上面 new 出来的对话框

void CDlgModeless::OnNcDestroy()
{
CDialog::OnNcDestroy();

delete this;
}

在 OK 和 Cancel 时，调用 DestroyWindow，它会发出 WM_NCDESTORY

void CDlgModeless::OnBnClickedOk()
{
if( UpdateData(true) )
DestroyWindow();
}

void CDlgModeless::OnBnClickedCancel()
{
DestroyWindow();
}