Please describe the problem:
This was reported on Launchpad: https://bugs.launchpad.net/ubuntu/+source/gnumeric/+bug/173311
by: https://bugs.launchpad.net/~l-wallner





Steps to reproduce:
1. Create a XY Plot in Gnumberic. 
2. Double click on the diagramm to open the customize chart dialog. 
3. Then select the "series1" element, and in the lower part of the dialog the "data" tab. 

Actual results:
There are three fields for entering data : "(Name)", "(X)", and Y.


Expected results:
Actually, as per the documentation, the brackets should indicate when a entry is optional (e.g. the name is optional, the plot will also work without the name). But the plot does not work without the "X" entry.

Does this happen every time?
Yes.

Other information:
Actually it would be very nice if the X-Field was indeed optional (the series could just use the data from another series). Many times i have data series which all share the same x-values, so there this would make things easier for me. So either, this feature should be implemented to make the x-values really optional, or simply the brackets around the "X" should be removed in the dialog