The BN_UNHILITE notification message is sent when the highlight should be removed from a button. The parent window of the button receives this notification message through the WM_COMMAND message.
BN_HILITE
BN_UNHILITE is the same as the BN_UNPUSHED notification message.
This notification message is provided for compatibility with applications written for versions of Windows earlier than version 3.0. New applications should use the BS_OWNERDRAW button style and the DRAWITEMSTRUCT structure for this task.
BN_HILITE, BN_UNPUSHED, DRAWITEMSTRUCT, WM_COMMAND, WM_DRAWITEM