For scientists, it is tempting to think of GUI development as a tedious but trivial task, best delegated to auxiliary personnel. Expect this approach to yield unstable software with unsatisfactory performance and an unmaintainable code base. Get a few basics right, and everything will be so much clearer and easier: Strictly separate the GUI layer from the scientific core. Dare using global variables to hold session and GUI state. Cache computational results. Ensure that the display is always up to date. Provide an emergency interrupt button. Foresee multithreading. Log user actions. Use a replay engine during development and for testing. Plan for scripting.