Color difference between drawRect and drawString

strange behaviour with color.
With source below, text is blue and rect is green
Looks like drawString expects color from 1 to 8 and drawRect expects 0 to 7

require("Font8x16").add(Graphics);
var grf = Graphics.createArrayBuffer(128,32,4,{interleavex:true});
grf.setBgColor(0);
grf.clear();
grf.setFont("8x16",size);
grf.setColor(2);
grf.drawString("my test",10,5);´
grf.drawRect(0,20,127,24);