CB_SETEXTENDEDUI
wParam = (WPARAM) (BOOL) fExtended; /* extended UI flag */
lParam = 0L; /* not used, must be zero */
An application sends a CB_SETEXTENDEDUI message to select either the default user interface or the extended user interface for a combo box that has the CBS_DROPDOWN or CBS_DROPDOWNLIST style.
fExtended
Value of wParam. Specifies whether the combo box should use the extended user interface or the default user interface. A value of TRUE selects the extended user interface; a value of FALSE selects the standard user interface.
The return value is CB_OKAY if the operation is successful, or it is CB_ERR if an error occurred.
The extended user interface differs from the default user interface in the following ways:
Clicking the static control displays the list box (CBS_DROPDOWNLIST style only).
Pressing the DOWN ARROW key displays the list box (F4 is disabled).
Scrolling in the static control is disabled when the item list is not visible (the arrow keys are disabled).
This example selects the extended user interface for a combo box:
SendDlgItemMessage
(hdlg, ID_MYCOMBOBOX, CB_SETEXTENDEDUI, TRUE, 0L);