Added a bunch more features to the pilot application, including saving/reloading state (very simple), sanity checks in case the icon directory is not where it's expected to be, the ability to change the icon directory, an About box, and some tweaks to make for more robust cross-platform compiles. Yesterday I test-compiled on Windows 7 and everything worked.
This phase of the project can now be said to be complete. I've confirmed that all the features we were interested in are present and practical in QT, and got a feel for how to develop a basic GUI application. Progress is much faster than I expected.