이렇게 하면...
   Screen = new TScreen(Application);

   long TaskBarH;
   APPBARDATA structBarData;

   long l, r, t, b;

   structBarData.cbSize = (unsigned long)sizeof(APPBARDATA);

   TaskBarH = SHAppBarMessage(ABM_GETTASKBARPOS, &structBarData);

   l = structBarData.rc.left;
   r = structBarData.rc.right;
   t = structBarData.rc.top;
   b = structBarData.rc.bottom;

   TrayPopupForm->Left = Screen->Width  - TrayPopupForm->Width;
   TrayPopupForm->Top  = t - TrayPopupForm->Height;