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.
A pointer to an NMHEADER structure that contains information on the header control.
No return value.
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.
Minimum supported client
|Windows Vista [desktop apps only]|
Minimum supported server
|Windows Server 2008 [desktop apps only]|