The CBN_SELENDCANCEL notification message is sent when the user clicks an item and then clicks another window or control to hide the list box of a combo box. This notification message is sent before the CBN_CLOSEUP notification message to indicate that the user's selection should be ignored.
wParam
Specifies the identifier of the combo box.
lParam
Specifies the handle of the combo box in the low-order word, and specifies the CBN_SELENDCANCEL notification message in the high-order word.
The CBN_SELENDCANCEL or CBN_SELENDOK notification message is sent even if the CBN_CLOSEUP notification message is not sent (as in the case of a combo box with the CBS_SIMPLE style).