DomainRules is a power/pro-feature and it's not meant to edit the setting within that *tiny text editor* but you should use a texteditor of your choice, best with json support (eg notepad++).
Also regex provides the MOST flexibel solution for easy and VERY complex use cases. Creating GUI editors/settings takes LOTs of time, time we don't have. Anyone is welcome to contribute and help with development.
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JD-Dev & Server-Admin
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