After maybe 10 hours of work, I now have a port of my current progress to Gtk+. This time included creating Makefiles, and writing all of the concrete Gtk+ classes from scratch. This is a very important milestone because it illustrates just how portable the core architecture is. Compared to the amount of effort that it took getting the first implementation of where I am at this point running on Cocoa, 10 hours is practically nothing, and is exactly the desired result for constructing a toolkit in this manner. This doesn't mean Cocoa or MacOS X was more difficult to develop for, it's just that by isolating the platform specifics as I have, my job in going to a new platform is dramatically easier (I expect the same amount of effort in going to Win32, though I will have to do a little more research into my choice of concrete toolkits -- Win32? Something else more .NET-ish? My guess is Win32 is the right choice, but we shall see. I'll supply more details regarding what I had to do to get a Gtk+ port in a later post. But for now, here is a screen shot: