The CBN_EDITUPDATE notification message is sent when the edit control portion of a combo box is about to display altered text. This notification message is sent after the control has formatted the text, but before it displays the text. The parent window of the combo box receives this notification message through the WM_COMMAND message.
CBN_EDITUPDATE
idComboBox = (int) LOWORD(wParam); // identifier of combo box
hwndComboBox = (HWND) lParam; // handle to combo box
If the combo box has the CBS_DROPDOWNLIST style, this notification message does not occur.
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Requires version 1.0 or later.
Header: Declared in winuser.h.
Combo Boxes Overview, Combo Box Messages, CBN_EDITCHANGE, WM_COMMAND