OS X standalone(no DAW) piano dashboard widgets

Sorry if posted in the wrong area. I couldn’t find a category for this question.

Please name all low resource OS X polyphonic standalone(no DAW) piano dashboard widgets that use the built-in Apple GM synth generator to always run in the background & can be controlled via usb midi controller.

Although not a dashboard widget I have since found a small enough (free) app to always stay open.

http://notahat.com/simplesynth/