/usr/share/applications/gtk3-demo.desktop is in gtk-3-examples 3.22.30-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 | [Desktop Entry]
Name=GTK+ Demo
Comment=GTK+ code examples and demonstrations
Exec=gtk3-demo
Icon=gtk3-demo
Terminal=false
Type=Application
StartupNotify=true
Categories=Development;GTK;
NoDisplay=true
|