Well, I finished the first chapter. I estimated it would be 25 pages long when I wrote the proposal, but it ended up only being 12 pages long. Interesting...
The next chapter looks to be the other way around. It looks like it'll actually exceed the estimated 25 page limit. It's amazing how much space a few bitmaps and graphics take up.
It's also interesting how close I pay attention to other people's books... I open the book and start counting pages in a chapter, number of figures, size of left and right columns, what the fonts look like and where they put the sidebars, warnings and tips, do they use bullets or numbered lists, how complex are their figures and screen shots, how much code, etc.
I don't think I'll ever look at a technical book the same again...
Next chapter is all about IS Variables...