       {
         if (diff > 0)
         {
-          // todo need to stop the notes that will be scrolled off
           grid[column_index][layer][visible_grid_set] <<= diff;
         }
         else


              visible_grid_set = x;
              eTempo.setValue(tempo[visible_grid_set] * 16);  // *4's for encoder detents and *4 for byte storage
              
              mode = PLAYING_ERASE_GRID_1;

              // redraw whole screen because grid change

    refresh      = true;

    // todo add display of currnet tempo with a horizontal bar, possibley show other layer tempos
    int temp2 = eTempo.getValue() / 4; // Div4 for encoder detents
    tempo[visible_grid_set] = temp2 / 4 ; // Div4 byte storage
    beatInterval[visible_grid_set] = 60000L / temp2;
  }

  // replace lines that may have been erased by play column movement
