Project: table
Task (moderate): If no selected cell, press Tab and 'Shift+Tab' key to the first cell. Press Tab key to change the selected cell to the next one. The rules are from left col to right col, change to the left of next row if no next cell in current row; change to the first cell of the table if no next row. The rules for 'Shift+Tab' is the opposite of the rules of Tab key.