private void formMousePressed(java.awt.event.MouseEvent evt)//GEN-FIRST:event_formMousePressed
    {//GEN-HEADEREND:event_formMousePressed
        if (evt.getButton() == MouseEvent.BUTTON1)
        {
            if (dc_selected != null)
            {
                if (dc_selected instanceof DCConector)
                {
                    if (((DCConector) dc_selected).getStart() == null)
                    {
                        //set start
                        ((DCConector) dc_selected).setStart(evt.getPoint());
                    }
                } else
                {
                    Point p = dc_selected.getPosition();
                    pres_point_dif = evt.getPoint();
                    pres_point_dif.x = pres_point_dif.x - p.x;
                    pres_point_dif.y = pres_point_dif.y - p.y;
                }
            }
        } else
        {
        }
    }//GEN-LAST:event_formMousePressed