GUI: when typing subnames, suggest existing subnames in a drop-down
When managing domain records, it often occurs that one needs to create a new record type for an existing domain. It would be handy to have some kind of dropdown for the record type when clicking on "+ add another value".
Clarified with the OP: The observation was that when clicking "add a new value" within the GUI to add a value for the same subdomain, the new record is restricted to be of the same type as in the row where you clicked "add another value". Records of a type that was previously not present at the subname cannot be added.
This is because the rows represent RRsets, which have a subname and type, and may have one or several values. The "add another value" button only allows modifying the RRset's value list.
However, it's true that if one wants to add a record with a new type, one currently has to open the "Create RRset" modal and type the full subname, even if it is already in use for another type. The intention of the OP is to avoid that (especially as some subnames currently are not fully visible due to #476, and may be hard to copy and paste).
Proposed alternative solution: when typing subnames, suggest existing subnames in a drop-down.