This feature is now part of GLPi 9.1

Pull request has been integrated in GLPi 9.1

Hello @armin01.

Planning will be reviewed in next release (9.1).

See this capture :

So events type will now have different colors.

Regards

Work in progress : https://github.com/glpi-project/glpi/pull/737

Work is in progress for this request

Hello, it's already an existing option. Use meta criteria (white plus icon) to achieve it.

NOT condition is also available.

See this screenshot :