xulrunner is already running, but is not responding
I use Firefox 63.0.3 to run a XULrunner demo which from matthewkastor ( url: https://github.com/matthewkastor/XULRunner-Examples )
with the command line : "C:\Program Files\Mozilla Firefox\firefox.exe" -app C:\helloWorld\application.ini
when i first start the application and close the app's window by click "X" button, the app's window exit but the firefox process which contain xulrunner demo remain.
thus, when i start the app twice and found the error message like this:
helloWorld is already running, but is not responding.The old Firefox process must be closed to open a new window.
How can I fix it? thanks for any response.