Error: " An invalid character was found in text content." when saving from grid (4280406)

There was definitely no problem with Toad versions prior to 9.1. I had 9.0, 8.6 and 8.0 before and used the "Save As..." export with the same statement.
Note: the problem is not with characters in the DATA from the database, its with the column HEADER (name of a column).

To reproduce this copy and paste the following into a SQL Editor:

select dummy as "ä" from dual;

Execute it and try to save the result as text (export format doesn't matter).

I just tried this using Toad 9.0 and Toad 9.1. I attempted to save the grid contents as delimited text into the clipboard and when using Toad 9.1 I got an error:

2.5 Message: An invalid character was found in text content.
.
Line:_12
Error also occurs in the case of special characters are included inside the query statement rather than the result column names.