Maybe I should describe what I am trying to achieve. I want the description box in the event edit view to be removed for one particular calendar category (The calendar category ‘Reservations’ in my case). If other calendar categories (such as teaching, etc.) are selected in the edit view, then the description box should be available.

My idea was to remove the description box entirely from the custom layout and use a custom field for it instead (which I then termed ‘Additional infos’). This is because I noticed in the custom field configuration that I can select applicable categories for this field (for which the custom field should be displayed as I understand). I deselected the category ‘Reservations’ from this list to make the custom field ‘Additiona Infos’ only available for other categories. This would then serve my purpose.

The custom field ‘Additional infos’, however, still appears when selecting the category ‘Reservations’ in the edit view. Shouldn’t it be gone when having removed it from the 'Applicable Categories' in the backend? Or am I thinking wrong here?

Another comment that I have is that when I selected ‘Allow HTML content’ for my custom field ‘Additional infos’ (which is a text area), I would not show me an HTML editor in the frontend.