I think it may be a backwards compatibility issue from long ago. I seem to remember Erel saying that that btn.Color = "0,0,0" was valid in very early versions of Basic4ppc in the IDE before the true compiler was introduced. Indeed you should see that when you run your program in the IDE the button has a black border that vanishes if you comment out that line. It looks like the IDE still accepts the syntax, but doesn't do the right thing with it anymore, while the code generator for the optimising compiler doesn't support this deprecated syntax at all.