I found out what I did wrong. I was lazy, so instead of defining two variables and calling GetGWorld (which also returns the current GDevice) I used the macro I usually use called SAVEGWORLD, which does all that, plus some more stuff (save the current fore/back colors and set the to black). Apparently the color things are not suppposed to be done in the middle of a color search procedure, so when I took those out (so instead of using the macro I actually defined the variables and called GetGWorld myself) it worked.

The rest of the day was spent implementing a line tool (that was really easy) and setting up AfterStep on MkLinux.