How to disable the "is not responding" message on Fedora
If this is a gnome based app, as it looks like, the function named delete_ping_timeout_func
is called whenever a timeout happens to show this popup.
The timeout is defined in the mutter source and is not configurable without recompiling the library as shown here.
#define PING_TIMEOUT_DELAY 5000
Use this extension to remove the popup. https://extensions.gnome.org/extension/2257/disable-force-quit-or-wait-button/