Okay, here's the stuff documenting ADCTL.H:

Macros:
-------------------------------------------------
HWND GetADEngineWindow()
   Returns the window handle of the main After Dark window.  Send any of the
messages documented below to this window.

UINT RegisterADNotifyMessage()
   Registers the After Dark sleeping notification message.  The return value
is the message ID.  This message is sent to all top-level windows when After
Dark is about to sleep.  Note that sleeping cannot be vetoed.

Messages:
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ADM_ENGINEASLEEP
    wParam not used.
    lParam not used.
    Returns 1 if After Dark is sleeping, 0 if it is not.

ADM_GETBANNERMESSAGE
    Gets the current banner message.  Only valid when engine is asleep.
    wParam = buffer length.
    lParam = LPSTR to buffer to receive message.  Can be NULL.
    Returns number of characters copied.  0 if nothing copied.  If lParam is
NULL, the message length is returned.

ADM_SETBANNERMESSAGE
    Sets the current banner message and starts the banner message.  Only
valid during sleeping.  Maximum banner length is 255 chars.
    wParam = 0.
    lParam = LPCSTR to banner message.
    Returns 1 if successful.  0 otherwise.

ADM_ENABLEBANNER
    Enables or disables the banner message.  Only valid during sleeping.  If
a banner message is not set, this message is ignored.
    wParam = 1 to enable banner, 0 to disable banner.
    lParam not used.
    Returns previous banner state.

ADM_BANNERENABLED
    Only valid if sleeping.
    wParam not used.
    lParam not used.
    Returns 1 if banner is set and enabled, 0 otherwise.

ADM_STARTSLEEPING
    Puts the engine into sleep using the currently selected module and AD
default.
    wParam = 0.
    lParam = 0.
    Returns 1 is sleeping initiated, 0 otherwise.

ADM_STOPSLEEPING
    Stops the engine from sleeping using the current AD defaults.
    wParam = 0.
    lParam = 0.
    Returns 1 if sleeping stopped, 0 otherwise.

ADM_ENABLESLEEPING
   Enables or disables sleeping in the engine.
   wParam = 1 to enable sleeping, 0 to disable.
   lParam not used.
   Previous sleeping enabled state is returned.

ADM_SLEEPINGENABLED
   Returns whether or not sleeping is enabled.
   wParam not used.
   lParam not used.
   1 is return if sleeping is enabled.  Otherwise, 0 is returned.