procedure TMainForm.ImageEnVect1MouseMove(Sender: TObject; Shift: TShiftState;
  X, Y: Integer);
var
  hobj: integer;
  R:TRect;
begin
  hobj := ImageEnVect1.FindObjectAt(x, y, Distance);
  if hobj<0 then   Exit;

 if (lasthobj > -1)  then begin
    ImageEnVect1.ObjPenColor[lasthobj] := clRed;
    lasthobj := -1;
  end;

  if (hobj > -1)  then begin
    if (lasthobj > -1) then begin
      ImageEnVect1.ObjPenColor[lasthobj] := clRed;
    end;
    ImageEnVect1.ObjPenColor[hobj] := clBlue;
    lasthobj := hobj;
  end;
end;