Final answer:
The 'Editor' or 'Spelling & Grammar' button in the Review tab likely opened the Editor task pane, used for proofreading and editing.
Step-by-step explanation:
The button that caused the Editor task pane to open in the current document is likely the 'Editor' or 'Spelling & Grammar' button in the Review tab of the toolbar ribbon in Microsoft Word. This feature is used for proofreading and editing documents, providing spelling, grammar, and stylistic suggestions. It is not to be confused with the Reviewing Pane, which specifically relates to tracking changes made to the document.
To ensure that changes you make to the document will not be saved as edits, you should go to the tools ribbon and toggle Track Changes to off. This prevents the document from marking every edit and change made as part of the revision process. If you want to view all changes in a pane, you would click Reviewing Pane in the tools ribbon. To navigate to a specific revision within the document, you can click on the revision listed in this pane.