A common dialog box sends the HELPMSGSTRING registered message to the window procedure of its owner window when the user clicks the Help button.
For Explorer-style Open and Save As dialog boxes, this message has been superseded by the CDN_HELP notification message.
MessageID = RegisterWindowMessage(HELPMSGSTRING);
hdlg = (HWND) wParam;
lpStruct = (LPVOID) lParam;
Parameters
hdlg
Handle of the common dialog box.
lpStruct
Pointer to the initialization structure for the common dialog box. This structure can be a CHOOSECOLOR, CHOOSEFONT, FINDREPLACE, OPENFILENAME, PRINTDLG or PAGESETUPDLG structure.
Return Values
No return value.
Remarks
You must specify the HELPMSGSTRING constant in a call to the RegisterWindowMessage function to get the identifier for the message sent by the dialog box.
When you create the dialog box, use the hwndOwner member of the initialization structure to identify the window to receive HELPMSGSTRING messages.
See Also
CDN_HELP, CHOOSECOLOR, CHOOSEFONT, FINDREPLACE, OPENFILENAME, PRINTDLG, PAGESETUPDLG, RegisterWindowMessage