The NMHDR structure contains information about a notification message. The pointer to this structure is specified as the lParam member of the WM_NOTIFY message.
typedef struct tagNMHDR {
HWND hwndFrom;
UINT idFrom;
UINT code;
} NMHDR;
Members
hwndFrom
Window handle of control sending message
idFrom
Identifier of control sending message
code
Specifies the notification code. This member can be a control-specific notification code, or it can be one of the following common notification values:
| Value | Meaning |
| NM_CLICK | The user has clicked the left mouse button within the control. |
| NM_DBLCLK | The user has double-clicked the left mouse button within the control. |
| NM_KILLFOCUS | The control has lost the input focus. |
| NM_OUTOFMEMORY | The control could not complete an operation because there was not enough memory available. |
| NM_RCLICK | The user has clicked the right mouse button within the control. |
| NM_RDBLCLK | The user has double-clicked the right mouse button within the control. |
| NM_RETURN | The control has the input focus, and the user has pressed the ENTER key. |
| NM_SETFOCUS | The control has received the input focus. |