When is a bug not a bug? When it’s an undocumented feature. This is an old industry joke that pokes fun at software vendors, who often dismiss unexpected behaviour in applications by pretending that nothing is wrong and that the software was really designed that way.

Two recent “bugs” reminded me of that joke, and both concerned spreadsheets: Microsoft’s Excel 2007 and the Calc application in the OpenOffice.org open source productivity suite.

Excel hit the headlines at the end of September with an issue affecting some calculations that produce a result around 65,535. The flaw only affects Excel 2007, and causes an incorrect result to be displayed. Microsoft downplayed the seriousness of this, stating that it is the displayed result and not the stored result that is affected, so that other calculations referencing that particular cell should be correct.
This might not reassure users whose business projections depend on such calculations, but at least Microsoft has promised a fix in the near future.

Perhaps more problematic is when a feature doesn’t perform as users expect, yet is regarded as functioning perfectly correctly by the vendor. Following the recent launch of OpenOffice.org version 2.3, a reader wrote to IT Week complaining about an issue he said has been vexing him and others since the first release, and which is still present in the new version.

At the heart of the issue is the AutoFilter function, which hides cells depending on their contents. This might be used so that only non-blank cells are displayed, for example. In Excel, the user can then perform an operation, such as filling the remaining blank cells with a particular value, while leaving the hidden cells unaffected.

However, in OpenOffice.org’s Calc spreadsheet, applying an operation to a selected row of cells will affect all of them, even if they are hidden. It seems that a very vocal minority of users has been trying to get this changed since the earliest days of the suite, but those managing the project insist the function exhibits the intended behaviour.

This raises the question of when exactly an issue should be regarded as a genuine bug. To the developers, AutoFilter works perfectly, while many of those posting comments on the OpenOffice.org forums regard it as a fatal flaw.

Perhaps as a compromise, it could provide a tickbox option “AutoFilter works like in Excel” for those that require this. Otherwise, it would seem a strange affair if Microsoft turned out to be more responsive to user feedback than an open source project.