Call this function to display the Windows common font dialog box and allow the user to choose a font.
IDOK or IDCANCEL. If IDCANCEL is returned, call the Windows CommDlgExtendedError function to determine whether an error occurred.
IDOK and IDCANCEL are constants that indicate whether the user selected the OK or Cancel button.
If you want to initialize the various font dialog controls by setting members of the m_cf structure, you should do this before calling DoModal, but after the dialog object is constructed.
If DoModal returns IDOK, you can call other member functions to retrieve the settings or information input by the user into the dialog box.