Glen, They are hiding the object with the help of conditional Show option of the charts. This option you could find in Layout tab of the charts.
At1st they are showing the Pivot table, in that pivot table the expression to show the pivot table would be GetSelectedCount(ProjectName)<>1.
Once the projectName is selected the other other are getting enable with the expresion in conditional show. the expression would look like GetSelectedCount(ID)=1
For more details look at the attached aplication.
bundel.qvw 148.0 K