The HDN_ITEMCHANGING notification message notifies a header control's parent window that the attributes of a header item are about to change. This notification message is sent in the form of a WM_NOTIFY message.
HDN_ITEMCHANGING
phdr = (HD_NOTIFY FAR *) lParam;
Parameters
phdr
Pointer to an HD_NOTIFY structure that contains information about the header control and the header item, including the attributes that are about to change.
Return Values
Returns FALSE to allow the changes or TRUE to prevent them.
See Also