Super Mario Advance 2 Level Select Glitch

Nintendo implemented a level select feature in super mario advance 2. They also didn't implement an unused copy of Donut Plains 1. If you do a glitch where you access the level select well walking down in Vanilla Dome 1, and choose Choco-Ghost House, you can walk of the normal map and go to a null area on the map screen. If you hold down when you walk off Chocolate Island, you will go down the latter and onto an unaccessable area, where the unused level is. If you don't, you will go to a never ending bonus game. Please go to the same goal I did when you attempt this.