In Sitecore (I'm specifically working with version 7.5 right now, but I believe this applies to other versions), when you mark a field as shared or unshared, you receive a popup that a lengthy background process has started. Is there any way to definitely determine when this process has finished?
while performing some actions (like you mentioned),there should be a master Index update based on your index strategy i.e by default it should be 'SYNCMASTER'. you can get the status of the background operation through JOB viewer through Sitecore Rocks. Below snapshot shows the background changing the process from 'QUEUED' to 'COMPLETED'