In chart edit mode, selecting a portion of a pie chart doesnt make the data series section appear in the sidebar.
Build ID: 2639eadce4c9ccead9112a6893b5e9e2e0fefd78
TinderBox: Linux-rpm_deb-x86_64@70-TDF, Branch:master, Time: 2015-09-14_23:56:58
Locale: en-US (en_US.UTF-8)
That does not sound like a bug. A single portion of the pie chart is not a data series, it is a data point. It is the same behavior as selecting a single bar in a bar chart or a single data point in a xy chart.
Yes you are correct that a data series is different from a point, so maybe a data point content panel could be created, that has a show checkbox and placement drop down menu for the data label, as the context menu has the entry for 'Insert Single Data Label', as that was what i was looking to have access to from the data series content panel.