I am finding that when there is a document library in SharePoint with checkin/checkout required, if a user with read-only ("Visitor") permissions opens a document from that library, the document will open as read-only in Word, Excel, etc., but the user will see the "Server Document" bar with the message "To modify this document, you must check it out" and the "check out" button. When the user tries to check the document out, they are asked to authenticate, and then receive the error "Cannot perform this operation. The file has been deleted or someone else has it checked out."
How is it possible to prevent a user with read-only rights in SharePoint from seeing the "Check out" option in Word or Excel?