In a dash board Pega version 8.6.3  my work list widget we were unable to expand  other case case with out collapsing   the already expanded existing case.

Step 1 : in Pega 8.6.3 v open the case manager portal dash board context.

Step 2 :  Open the worklist widget and  expand the parent case

Step 3 :  And try to open the another parent case 

Step 4: with out collapsing the first one we could not expoand the 2nd case not an issue in lower verions of pega 8.4.