Author: Jonas Bilinkevicius 

I wonder if anyone can help me. I am trying to capture when the mouse button is 
pressed on the desktop wallpaper (excluding icons if possible).

Answer:

This returns the same handle:

1   function GetDesktopListViewHandle: THandle;
2   var
3     S: string;
4   begin
5     Result := FindWindow('ProgMan', nil);
6     Result := GetWindow(Result, GW_CHILD);
7     Result := GetWindow(Result, GW_CHILD);
8     SetLength(S, 40);
9     GetClassName(Result, PChar(S), 39);
10    if PChar(S) <> 'SysListView32' then
11      Result := 0;
12  end;
13  
14  procedure TForm1.Timer1Timer(Sender: TObject);
15  var
16    CursorPos: TPoint;
17    h: THandle;
18  begin
19    GetCursorPos(CursorPos);
20    h := WindowFromPoint(CursorPos);
21    Label1.Caption := IntToStr(h);
22  end;
23  
24  procedure TForm1.FormShow(Sender: TObject);
25  begin
26    Label2.Caption := IntToStr(GetDesktopListViewHandle); { GetDeskTopWindow); }
27    Timer1.Enabled := True;
28  end;