The CDM_HIDECONTROL message hides the specified control in an Explorer-style Open or Save As common dialog box. The dialog box must have been created with the OFN_EXPLORER flag; otherwise, the message fails.
CDM_HIDECONTROL wParam = (WPARAM) id; lParam = 0; // corresponding macro void CommDlg_OpenSave_HideControl(hdlg, id);
No return value.