There is no confirmation popup when leaving pages with unsaved data

Steps to reproduce
1. Open topic creation page
2. Fill "Title" and "Message content" field with valid data
3. Follow some link to go out from page

Actual result Selected link is opened

Expected result Confirmation popup with text like "Are you sure want to navigate away from this page? Press OK to continue, or Cancel to stay on the current page." should be shown

Note
Same problem presents on all pages which may contain unsaved data (editing posts, composing private messages and so on)