A while ago I read about the EGLFS plugin for QT (which is a GUI library). This plugin enable QT to draw directly to the Linux frame buffer. Which is ideal if you are running a GUI application on a embedded (low on resources) device and don't want the overhead of a full blown X11 + window manager desktop. This tutorial will walk you through the compilation and installation of QT5 (5.2 in my case) on a Raspberry Pi.
A while ago I wrote about the plans of using the Raspberry Pi as a synthesizer for the Midi keyboard. You can read about the steps to get this working on Windows over here. But this post is about getting it to work with the Raspberry Pi step-by-step.