What is the difference between penFore, penBack, fillFore and fillBack?

This confuses most people, but once you get the hang of it you'll find it very useful. The Macintosh color system is set up with the appearance of black "ink" on top of a white "canvas." In this metaphor, the foreground color refers to the "pen" and the background color refers to the canvas. As you can guess, the penFore is the foreground color to be used to draw the outline of an object, such as a button. The fillFore is the foreground color of the fill pattern. In SuperCard, fill patterns and color can be applied to not only graphics, but also to buttons and fields as well. Here's why this is worth knowing about: Suppose you want to develop an application which may be viewed on both color and monochrome monitors. By carefully applying the appropriate pattern, fillFore, fillBack, penFore and penBack properties (settable from the Colors and Patterns palettes in the Project Editor), you can determine which colors will be mapped to black and which ones will be mapped to white in a monochrome setup, with black corresponding to the penFore and fillFore, and white corresponding to the penBack and fillBack.