The icon in the tray of a application I can edit / add file associations with has disappeared. So how can I open this application?

I thought it was the icon of "Enable files associations", but double clicking it on the desktop doesn't open any program.

Check you didn't uninstall KeyFileAssoc software (see folder with same name in Liberkey\Apps folder)
If you did not have it anymore, download the platform version of Liberkey and just copy/paste KeyfileAssoc folder into your Liberkey\Apps folder

Many thanks Dji,

On the next start up of Windows, the icon in the tray appeared again. Very strange.

So I assume next time I could start the application by clicking the exe file in the applications folder.

Many thanks again, nice greetings, Dirk