Holy cow, I wrote a book!
Exercise: Explain why we used 0x7FFF to represent infinite height.
Answer: Commenter "Reiko" got this right. 0x7FFF is the maximum integer
coordinate supported by Windows 95, 98 and Me.
Exercise: Explain the line rcWindow.bottom += rcTemp.top.
rcWindow.bottom += rcTemp.top
Answer: The more precise way of writing the line would have been
rcWindow.bottom += (rcTemp.top - rcWindow.top) - (0 - rcWindow.top);