When the tickets list has been sorted by one of the header columns the links to sort by the other columns or reverse the sorting on the current column are incorrect.
To reproduce go to the URL: http://bugs.traq.io/traq/tickets?order_by=created_at.asc
All of the columns will now link to http://bugs.traq.io/traq/tickets
They should link to http://bugs.traq.io/traq/tickets?order_by=COLUMN_NAME.asc
and the currently sorted column should link to http://bugs.traq.io/traq/tickets?order_by=COLUMN_NAME.desc