Javamin Composer is a music composer written in Java. Javamin Composer consists of a rectangular "play" area. By hovering the mouse over this area, a tone plays. Left/right controls pitch and up/down controls note length.
a song can be created by clicking and manipulating the "play area"
the name is derived from the Theremin instrument. Which is played by waving your hands around in a field around the device. the mouse movements slightly emulate this.

The license of this software is Free, you can free download and free use this music composer software.