How to do this:
a workflow application running in the standard WorkSpace, LiveCycle ES2.5,
a user is assigned a Task,
he opens the form, processes it, then clicks a button to route the form to the next participant in the process,
at that moment, is there a way to let him manually select the next participant?
Out-of-the-box there is no way to manually select the next participant in the workflow. It may be possible by customizing Workspace.