DiaCanvas is a library for drawing diagrams. It is completely Model/View/Controller based and has a Visio (DIA) look. The package also contains a Python wrapper for the library.
This is a small program that lets you set MIDI controller values using sliders and buttons in a GTK+ window. The GUI is an XML-based Glade file which can be replaced without rebuilding the program, so you can build your own controller GUIs in Glade.