Bug #522243: Not display # N/A series in a chart

[Jean Brefort <jean brefort normalesup org>]

Hi,

Before doing anything for this bug, I would like to know what people
want, in general. The question here is what should be done with series
containing error values when dealing with the legend (errors are not
displayed otherwise, as far as I know).
We have several options:

1. don't display the series in the legend when it's name is actually an
error message such as "#N/A";

2. don't display the series if all it's data are error values, even if
it's name is valid.

3. don't display the series when the series has no valid data.

4. always display the series, and rely on the user to uncheck the "Show
in Legend" box if he does not want to see it in the legend.

Currently option 4 is already there. Option 1 would be easy to
implement, and option 2 and 3 are just a bit more tricky, but quite
feasable anyway (but not my preferred). Some people might want to see
all series in the legend whatever are the data, so I'm wondering if I
should do something and what, or just mark this bug as WONTFIX.

Regards,
Jean

P.S.: We might also change the "Show in Legend" logic to allow for more
options such as never, always and only when there are valid data, might
be option #5.