   tft.fillRect(FREQ_OFFSET_X+CHAR_WIDTH*2, 44, 2, 6, FREQ_FG);
   tft.fillRect(FREQ_OFFSET_X+CHAR_WIDTH*5, 44, 2, 6, FREQ_FG);
 
+  // draw the 'edge of digits' markers
+  for (int i = 0; i < NUM_F_CHAR; ++i)
+  { 
+    uint16_t x = char_x_offset[i];
+    
+    tft.drawFastVLine(x, 44, 6, ILI9341_RED);
+  }
+  
   // show the frequency
   display_frequency();
 }

    switch (event->event)
    {
      case event_Down:
        // see if DOWN is on a VFO frequency digit
        if (y < DEPTH_FREQ_DISPLAY + 30)    // a bit of 'slop' allowed
        {
          for (int i = 0; i < NUM_F_CHAR; ++i)
          {
//            Serial.printf("Comparing %d against %d, %d\n", x, char_x_offset[i], char_x_offset[i+1]);
            if ((x > char_x_offset[i]) && (x < char_x_offset[i+1]))
            {
              // within char 'bucket'

    if (event->event == event_None)
      break;

//    Serial.printf("Event: %s\n", event2display(event));

    uint16_t x = event->x;
    uint16_t y = event->y;
