I installed a fresh copy of Polyphone and the Keyboard will not display.
I tried all the setting from full all the way down and nothing. I then uninstalled the program, looked for any remaining files in both the Programs Files and the Program Files (x86) folders, making sure there was nothing remaining,than reinstalled the application but the keyboard will not display.
the keyboard is not always displayed, you have to open a soundfont and select an instrument or preset and the keyboard will appear like you set it in View.
regards