This window can be called up from the `windows' menu. It displays a five octave keyboard which can be used to transmit MIDI note on and note off events by clicking on the appropriate notes. The notes are played at velocity 64 unless the shift key is held down in which case the notes are played at velocity 127. There is the usual short delay between clicking on a note and something happening due to GEM checking for a double click. Because this is annoying with the virtual keyboard, when you hold down the `ALT' (or shift) key and click on the virtual keyboard it grabs control off the mouse, eliminating further delays until the key(s) are released.
The virtual keyboard is most useful when you are using a Korg M1R and don't have a MIDI merge box to merge note events from a MIDI keyboard into the SYSEX stream.