Problems with setColor and drawLine

What am I doing wrong here?

Bangle.setLCDMode();                                // use normal display mode
  g.clear();

  const Width = g.getWidth();
  const Height = g.getHeight();
  
  for (let x = 0; x < Width; x++) {
    g.setColor(x,0,0);
    g.drawLine(x,0, x,Height-1);
  }

In the emulator, the screen is filled with a constant red color - and not the gradient I would expect.

So where is the mistake?

Thanks in advance for any help!

Kind regards,

Andreas Rozek