[bitwize]

It was a common technique in the DOS era to simulate GUIs with text. This was not just done with the characters in codepage 437 either; using redefinable character sets in the EGA and VGA, graphical elements such as buttons, input fields, etc. could be rendered in character cells. By redefining characters where the mouse pointer was supposed to be, a pixel-accurate mouse pointer could be created. Not just trackers used this technique, but e.g., later versions of Norton Utilities did as well.