Figure 17.6 does not draw the diagonal green line as described in the paragraph above it that references Figure 17.6
Fig. 17-6 in my iBooks version does show the diagonal green line; my print version does not. Did the green line “fall out” when the image was screened for black and white publication? Maybe for the next edition, a different color diagonal line in Fig. 17-6 will survive the B&W screening for print.
Flipping through the book for color, there is not a whole lot about color in the book. Chapter 5 covers NSColor and color wells and this chapter touches on color as well, but I haven’t seen much else on color. There are too many other things to cover in a programming book. That makes it hard to justify a page or two of color plates for figures like this.