Is it possible to combine a Dropdown field with a plain text input field? I'm in ModelAdmin and would like to customize a DataObject's varchar field via getCMSFields() to display a dropdown of options as well as an area to add custom input if applicable.

E.g.

"Reason"

[Select]
"reason 1"
"reason 2"
"reason 3"
"other"

[Text] (input used when other selected)

I haven't found a matching fieldtype for this, but am thinking CompositeField(?)

Thanks ahead!