Google Drive and Docs Tips
See all Comments in a Google Doc - even resolved ones
Click on the "Comments" button at the top of a Google Doc to see all comments and discussions that have taken place in a document or presentation.
Comments and discussions work best in a document when they are tagged to a word or sentence and appear on the right side of the document. But you can see all document discussions in a list by clicking on the "Comments" button at the top of your document and selecting "Show comment stream" - you can also set how you are notified when collaborators post a comment.
Tip Update: Now just clicking on the Comments button opens up a summary of all comments, and you can click on the Notifications settings link in the top right to set your notifications.
This is really useful if a discussion has been "resolved" but you want to check the comment stream, or even re-open a debate.