When using PC-native file formats such as PDF or spreadsheets, users feel like they're interacting with a PC application. Because users are no longer browsing a website, they shouldn't be given a browser UI.

Users are easily confused when websites link them to non-Web documents that offer a significantly different user experience than that of browsing Web pages.

Jakob Nielsen gives the following guidelines:

- Open non-web documents in a new browser window.
- Warn users in advance that a new window will appear.
- Remove the browser chrome (such as the back button) from the new window.

Jakob Nielsen's Alertbox, August 29, 2005