I have noticed that the selection cursor, when hovering over a scatter plot
in the Windows version of Excel (2003 and 2007 versions), will display the
value of the data point the cursor is supposedly pointing at. This is a
handy feature, however, there appears to be a bug that directly impacts
accuracy of measurements taken from charts when using this feature.

I wrote "supposedly," because the data values displayed when hovering the
mouse over a data set in the chart are for a datapoint about 5-8 pixels to
the right, not the one at the tip of the arrow! This is an offset effect
that is peculiar to Excel charts.

I have tried this on several machines with different graphics cards, all
running WIndiows XP SP2 and two versions of Excel (2003 and 2007); all with
the same results. I have also tried it using a freeware utility called MB
Ruler, which provides a loupe to see the cursor hotspot magnified, so you can
see the effect very clearly.

The offset is not there for selecting cells in the worksheet or using other
features of the windows desktop, such as task bar buttons; it only happens
with the Excel charts. It appears that the charts, as displayed on a Windows
machine, are actually the thing that is offset slightly from where the
program thinks they are.

This problem is reportedly not present on the Excel 2004 for the Macintosh.

This problem has been verified to exist with other users and there does not
apper to be a solution for it. Perhaps MS needs to fix it.
--
Bas V