The current total lines of code is 277. I expect it to be about this number once I'm finished.
I'm writing it using Visual C++ Express, a free version of Visual Studio. Free (after free registration). From Microsoft. Very cool :)
So far I have screen splitting working correctly. My clip code is kinda borked. After I fix that, it should be completely trivial to add mouse movement calls. Since Windows doesn't typically use sloppy focus, I think I'll add extra code to figure out what window the mouse is over and give that window focus.