Delphi: How to respond to WM_SettingChange/WM_WinIniChange?

Posted by Ian Boyd on Stack Overflow See other posts from Stack Overflow or by Ian Boyd
Published on 2010-05-12T19:13:57Z Indexed on 2010/05/12 19:34 UTC
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i need to know when my application recieves a WM_SETTINGCHANGE message (formerly known as WM_WININICHANGE).

Problem is that the message pump in TApplication sends it down a black hole (default handler) before i can get a chance to see it:

procedure TApplication.WndProc(var Message: TMessage);
...
begin
   Message.Result := 0;

   for I := 0 to FWindowHooks.Count - 1 do
      if TWindowHook(FWindowHooks[I]^)(Message) then Exit;

   CheckIniChange(Message);

   with Message do
      case Msg of
      WM_SETTINGCHANGE:
         begin
            Mouse.SettingChanged(wParam);
            Default;   <----------------------*poof* down the sink hole
         end;
      ...
      end;
      ...
end;

The procedure CheckIniChange() doesn't throw any event i can handle, neither does Mouse.SettingChanged().

And once the code path reaches Default, it is sent down the DefWindowProc drain hole, never to be seen again (since the first thing the WndProc does is set the Message.Result to zero.

i was hoping to assign a handler to a TApplicationEvents.OnMessage event:

procedure TdmGlobal.ApplicationEvents1Message(var Msg: tagMSG; var Handled: Boolean);
begin
   case Msg.message of
   WM_SETTINGCHANGE:
      begin
         // Code
      end;
   end;
end;

But the OnMessage event is only thrown for messages that come through the message pump. Since the WM_SETTINGCHANGE message is "handled", it never sees the

PeekMessage
TranslateMessage
DispatchMessage

system.

How can i respond to the windows broadcast WM_SETTINGCHANGE?

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