LBN_SELCHANGE
idListBox = LOWORD(wParam);
hwndListBox = (HWND)lParam;
The LBN_SELCHANGE notification message is sent when the selection in a list box is about to change. The parent window of the list box receives this notification message through a WM_COMMAND message.
idListBox
Value of low word of wParam. Specifies the list-box ID.
hwndListBox
Value of lParam. Specifies the list-box window handle.
This message applies only to list-box controls that have LBS_NOTIFY style.
WM_COMMAND