grid editing error - like : col 0 has undefined origin

How to repeat:

select ASCII(word),word from table
where word regexp '[^[.NUL.]-[.DEL.]]'
and ASCII(term) > 197

Then try to edit word field

to find something, put forinstance 'Говедо' into that field

This (editing )should work, right ?
We have resultset only from one table.

Column 0 is what you select via ASCII(), that's where HeidiSQL currently blocks editing the whole result if there is one such computed column. To enable editing, be sure to select at least the primary key, or just all columns if the table does not have a PK. And don't select computed values.