message: Fix crash when event count is 1
diff: @@ -1739,7 +1739,8 @@ void TraceWin::graph_render_eventlist_selection( class graph_info_t &gi )
  {
  // Draw rectangle for visible event list contents
  if ( is_valid_id( m_eventlist.start_eventid ) &&
  - is_valid_id( m_eventlist.end_eventid ) )
  + is_valid_id( m_eventlist.end_eventid ) &&
  + ( m_eventlist.end_eventid > 0 ) )
  {
  trace_event_t &event0 = get_event( m_eventlist.start_eventid );
  trace_event_t &event1 = get_event( m_eventlist.end_eventid - 1 );
  