Checker 4

Notes: This version is a combination of checker 2 and 3. It uses the child window approach to controlling the checks but adds in the keyboard support. It uses setFocus to control which block the keyboard operations will be performed on and indicates this focus with a dashed rectangle.

Description: A screenshot of a program in front of a window containing code. The program has a series of horizontal and vertical lines that create a grid. Some of the boxes in the grids have a line going from the upper left corner to the bottom right corner and a line going from the upper right corner to the bottom left corner. One of the boxes has a dashed rectangle inside of it.