Currently, when the length of the WebDAV URL is longer than 259, the 'Open in MS Office' feature does not work any more, and an error of 'The URL of this file is too long for the application. A temporary copy of this file will be opened on your computer. You must save this copy as a new file.' is shown on the UI.
This may affect the usability of the Document and Media portlet and it would be better if we could improve the portal's current behavior.