1st cell
2nd cell
3rd cell

Move to one of the cell and then to another and another ... As you can see, Opera paint all borders only first-time and then none (move to upper cells) or only top border (move to lower cells). This affect only Opera 7.5x series and older versions of Opera (tested only 7.23) are OK. REGRESSION BUG
You can test it in older Operas and report result to discussion.
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