Display Cumulated Working Groups in Row Chart

Displaying Cumulated Working Groups instead of Working Groups
in the Row Chart allows to answer question 2. of the reference
list:

3. Who are the authors that have participated in more than one
   working group (what we call bridge authors)?

This can be answered by clicking all the following rows in the chart:
* WG I+II
* WG I+III
* WG I+II+III
* WG II+III
while leaving the other 3 rows unselected:
* WG I
* WG II
* WG III

The same configuration also answers question 5. by looking at the pie charts:

5. What kind of roles do the authors who participate in more than one
   working group occupy?