"Graphics.h"

GrMapColorRGB():

In GrMapColorRGB(), the last parameter (color index) is interpreted as a pointer to a word by the C stub, as opposed to one to a byte-sized value. As a result, if a pointer to a variable of type Color is passed, this may cause the byte immediately following the variable to be overwritten.
Workaround: use a word variable to hold the return value and cast it to type Color after that.

{Marcus Groeber}