WM_ENABLE
fEnabled = (BOOL) wParam; /* the enabled/disabled flag */The WM_ENABLE message is sent when an application changes the enabled state of a window. It is sent to the window whose enabled state is changing. This message is sent before the EnableWindow function returns but after the enabled state (WS_DISABLE style bit) of the window has changed.
fEnabled
Value of wParam. Specifies whether the window has been enabled or disabled. This parameter is TRUE if the window has been enabled; it is FALSE if the window has been disabled.
An application should return zero if it processes this message.