Use the framework provided GlobalInterruptEnable() function instead of the AVR8/XMEGA specific sei() macro, for future demo/project portability.

Projects/SerialToLCD/SerialToLCD.c

@@ -83,7 +83,7 @@ int main(void)
 
 	RingBuffer_InitBuffer(&FromHost_Buffer, FromHost_Buffer_Data, sizeof(FromHost_Buffer_Data));
 
-	sei();
+	GlobalInterruptEnable();
 
 	for (;;)
 	{