Toggle Black and White Background Color (Tip #2209) from Watson Kilbourne is not exactly a programmer utility but fits into the AutoCAD power user category. The goal of this routine is to change your screen background between black and white while leaving the cursor crosshair colors untouched. Load the LISP code and type TWB to flip between the background options. Power AutoCAD users who have a particular preference for one background or another while also using alternative colors for the crosshair will enjoy having this utility in their arsenal when visiting other people's workstations. This function is a great example of how to programmatically manipulate items inside the AutoCAD system.