helloSystem
Start showing a bouncing icon in the Dock
Start showing an animated icon in the Dock from the time launch is about to start the application onwards.
The Dock is then responsible for stopping the animated icon and show the regular application icon in case the app has launched, or just remove the animated icon altogether after a timeout, or in case the application exits.
Is there already a protocol/standard for this?
https://www.freedesktop.org/wiki/Specifications/startup-notification-spec/
Still at 0.1 after 18 years! https://specifications.freedesktop.org/startup-notification-spec/startup-notification-0.1.txt
It uses "X messages", a mechanism for sending text strings between X clients without the need for D-Bus. Interesting!
In the language of that spec, the launch command is called a "Launcher".
The startup notification protocol involves sending X messages with the message_type atom _NET_STARTUP_INFO_BEGIN/_NET_STARTUP_INFO to the root window.
Possibly relevant code:
https://github.com/qtinsider/qt5-meego-platform-plugin/blob/ceb11993600bfcf7aecd0e5bc5e645e26556cb1f/mplatformscreen.cpp#L315-L339
There is even a whole library for it: https://github.com/freedesktop/startup-notification