I need my users to be able to see all workflows, whether they are the owner or not.
I changed public-services-security-context.xml (v4.2.e) where bean WorkflowService_security is now class org.alfresco.repo.security.permissions.impl.AlwaysProceedMethodInterceptor.
That helped my users view "All Active Tasks" (dashlet). But what about Completed Tasks (dashlet)?
You also need to fetch those task and add them into list of tasks. I have not checked exactly how it is done in share but in Alfresco webclient I had done this by using workflow service to fetch all completed tasks then added that list to regular list which is being rendered on UI. Hope this will give you right direction for implementing it in share.
java.util.List getWorkflowsForContent(org.alfresco.service.cmr.repository.NodeRef packageItem, boolean active) Gets the Workflows that act upon the specified Repository content.
if you pass boolean value as false it will return you all completed workflows for particular content.Then you can add that list to existing list. May be use can user other apis as well as per your need.