HDN_DROPDOWN notification code

Sent by a header control to its parent when the drop-down arrow on the header control is clicked. This notification code is sent in the form of a WM_NOTIFY message.

HDN_DROPDOWN
        
    pNMHeader = (LPNMHEADER) lParam;

Parameters

lParam

A pointer to an NMHEADER structure that contains information on the header control.

Return value

No return value.

Remarks

The example in the Syntax section shows how the notification receiver casts LPARAM to retrieve the NMHEADER structure. WPARAM contains the ID of the control that sends this message.

This message is sent only if style HDF_SPLITBUTTON is set on the header item.

Requirements