Want a minimal music composing program to import into another project? This program by Kevin is a one-sprite version of the composing_no_keyboard program, made possible in Scratch 1.1, which finally allows polyphony in a single sprite. (The java interpreter still doesn't seem able to handle polyphony---at least not on my Mac.)
The composer works with notes of a scale, which it then converts to pitches on a major scale (C major by default, but transposing is trivial by changing the base note).
As with many scratch programs, the timing seems a bit messed up in the java implementation---downloading and running on scratch works better.
Just click on the stage to start or stop the music. You may have to wait for the music to get to the end of the phrase.