Dear Bertalan, thank You very much for the new version of the Lilypondtool! For the virtual piano, that can make use of midi, I've been waiting for a long time. But I have two problems with this plugin (which, I guess, can be solved easily):
When the piano is switched on, it is not so comfortable to switch to reactivate the main window in Lilypondtool. I didn't find a shortcut for this.
I couldn't change the shortcut for entering the 8th note to q (I usually prefer entering durations with the left hand).