Author: William Gerbert 

Answer:

Sometimes the taskbar covers a part of your application window and you would like 
to avoid that. The following procedure shows how to retrieve the size of the 
taskbar ('tray window'); the key information is the internal window's classname 
Shell_TrayWnd:


1   procedure TForm1.Button1Click(Sender: TObject);
2   var
3     Tasklist: HWnd;
4     Bordered: TRect;
5   begin
6     Tasklist := FindWindow('Shell_TrayWnd', nil);
7     GetWindowRect(Tasklist, Bordered);
8     Label1.Caption := 'Left: ' + IntToStr(Bordered.Left);
9     Label2.Caption := 'Right: ' + IntToStr(Bordered.Right);
10    Label3.Caption := 'Top: ' + IntToStr(Bordered.Top);
11    Label4.Caption := 'Bottom: ' + IntToStr(Bordered.Bottom);
12  end;



Note:
The taskbar window is always two pixels broader or higher than the screen, e.g. at a screen resolution of 800x600, the with would be 802 pixels.