Just picked up a significant bug in the Data Element Group Editor:
1. Open DEG editor, and select a DE group with existing members.
2. If required, filter the list of available elements.
3. First bug: data elements that already ARE group members are not
excluded from the available list.
4. Second bug: you can select an existing group member and select it -
that element gets duplicated at the bottom of the group member list.
I have not checked if that duplicated member records is actually added
to the database, messing it up - or whether the duplication is a
display/interface issue only.