#include <Adafruit_RGBLCDShield.h>
#include <utility/Adafruit_MCP23017.h>
Adafruit_RGBLCDShield lcd = Adafruit_RGBLCDShield();


void setup() {
  lcd.begin(16, 2); //format of display
}

int menu = 0;
int subMenu = 99;

int debounce = 200;
unsigned long pMillis = 0,
              cMillis;

void loop() {
  uint8_t buttons = lcd.readButtons();

  cMillis = millis(); // sets cMillis to current millis()

  lcd.setCursor(0,0);
  if(cMillis >= (pMillis + debounce)){

    if (menu == 0) {
    lcd.print("Select menu option");
      if (buttons & BUTTON_SELECT) {
        lcd.clear();
        menu = 99;
        subMenu = 1;
      }
    }

    if (subMenu == 1) {
      lcd.print("in sub menu 1");
      if (buttons & BUTTON_SELECT) {
         lcd.clear();
         lcd.setCursor(0,1);
         lcd.print("shouldnt happen");
      }
    }
  pMillis = cMillis; // sets pMillis to cMillis for the next iteration of the loop()
  }

  if(cMillis < pMillis){
    pMillis = cMillis; // sets pMillis to cMillis for the next iteration of the loop()
  }

}