Customizing field names in PT's is important - see bug 129088. But we should be able to do that ex-post-facto as well. And what better way to edit a PT field name than in-sheet, in-cell editing - in the cell where that name is shown? In fact, we can already perform the edit - we just get an error message when finalizing it (e.g. with Enter): "You cannot change this part of the PivotTable". Let us change it!
*** This bug has been marked as a duplicate of bug 162595 ***