procedure TForm1.TimerScreenshotTimer(Sender: TObject);
var
  pt: Winapi.Windows.TPoint;
  h, hc: Winapi.Windows.HWND;
  r: TRect;
  DC: HDC;
  GrandchildrenList: ^TWindowHandleList;
begin
  if not (GetKeyState(VK_CONTROL) < 0) then EXIT; // if not CTRL key is pressed then exit

  Winapi.Windows.GetCursorPos(pt); // get mousepointer position

  if Winapi.Windows.PtInRect(Self.BoundsRect, pt) then EXIT; // Exclude mouse over own window

  h := Winapi.Windows.WindowFromPoint(pt); // Handle of the WINDOW under the mouse pointer
  hc := Winapi.Windows.ChildWindowFromPoint(h, pt); // Handle of the WINDOW's child control

  // Iterate through all the control's children (if it has any):
  if GetKeyState(VK_SHIFT) < 0 then // if SHIFT key is pressed
  begin
    GrandchildrenCount := 0;
    EnumChildWindows(Hc, @CountGrandchildrenCallback, LPARAM(@GrandchildrenCount)); // wrong GrandchildrenCount
    CodeSite.Send('TForm1.TimerScreenshotTimer: GrandchildrenCount', GrandchildrenCount);
    // Question: How to iterate through ALL the control's children (if it has any) with the SHIFT key?
    // This only gets the control's FIRST child:
    if GetKeyState(VK_SHIFT) < 0 then // if SHIFT key is pressed
	    hc := Winapi.Windows.GetNextWindow(hc, GW_HWNDNEXT); // Get the first grandchild
  end;

  // Draw a red frame around the control:
  Winapi.Windows.GetWindowRect(hc, r);
  DC := GetWindowDC(0);
  try
    // Invalidate the previous control's rectangle:
    if prevHc <> 0 then
    begin
      Winapi.Windows.GetWindowRect(prevHc, prevR);      // get previous frame
      InvalidateRect(GetDesktopWindow(), @prevR, True); // remove previous frame: seems it does not work?
    end;

    // Draw the frame around the new control:
    FrameRect(DC, r, CreateSolidBrush(RGB(255, 0, 0)));
  finally
    ReleaseDC(0, DC);
  end;
  prevHc := hc;

  // Show the Control under the mouse pointer in the TImageEnView control:
  if hc <> 0 then
  begin
    if ImageEnView1.IO.CaptureFromScreen(iecsSpecifiedWindow, -1, hc) = False then
    begin
      ImageEnView1.IO.CaptureFromScreen(iecsSpecifiedWindow2, -1, hc);
    end;
  end;
end;