RowEditor makes an empty column contain "" after editing another column

[mother]

Hi all,

I have a grid where the last column contains no data, eg

            data.push({
                name: 'abcd',
                address: 'efg',
                email: 'a@b.com',
                freetime: 0.5,
                tags: ''
            });

Once I edit a column using the RowEditor plugin, and for example, change name to 'defg', the name column field is marked 'dirty' as expected, but so is the tags field, where I made no changes. Dumping the content of the store before results in:

console.log(r.data['tags']);

(an empty string)

and after the edit:

[""]

It appears RowEditor modifies the field even if it's empty. Is there a way to fix this behavior?

Update: investigating further, the strings when the store is created are zero-length, but after 'Update' is clicked on RowEditor, the length of the tags field is now one. I haven't been able to determine what this single character is, but I'm guessing \0.
Cheers,

Mike