SlackBuildsOrg/multimedia/vkeybd

vkeybd is a virtual keyboard for AWE/OSS, MIDI/OSS and ALSA drivers.  It is 
a simple fake of a MIDI keyboard on X-windows system. Enjoy music with your 
mouse and computer keyboard.

Make sure to have a MIDI synth configured in order to play music with this 
program - if you use the optional dependency TiMidity++, for example, run
it in ALSA server mode (timidity -iA) before starting vkeybd, then use
aconnect to link the ALSA sequencer input (vkeybd) and output (timidity)
ports.

Also, you may want to provide a custom keymap to vkeybd (~/.vkeybdmap)