Very flickery display when showing clock

[FrankHovis]

Around line 460 of marquee.ino the commands

matrix.fillScreen(LOW);
centerPrint(currentTime, true);

are looped though as fast as the main loop executes resulting in 10's of matrix updates per seconds and lots of flickering of the display with random dots being much brighter etc.

I added

  LEDMillis = millis();  
  if (LEDMillis - LEDnowMillis >= 1000)  
  {
    LEDnowMillis = LEDMillis;  //save the start time.
    matrix.fillScreen(LOW);
    centerPrint(currentTime, true);
  }

around these calls (with the needed global declarations as unsigned long) as a workaround, but its probably not an ideal way to do it. It stops the flickering.