To reproduce:

1. Open Brackets to the Getting Started folder and select index.html from under the getting started folder. Do not edit the source or double-click the filename as this will move it to the Working Files and fail to reproduce the behavior
2. Press the Live Preview button
3. Using the mouse, move the cursor to different block regions in the index.html source and notice the highlighted region updates in the browser instance
4. In Brackets select the main.css file from under Getting started.
5. Using the mouse, move the cursor to different css selectors in the main.css source and notice the highlighted region updates in the browser instance
6. Switch back to index.html and move the cursor to different block regions and notice that live updates do not occur.

Workaround:
Before enabling live preview double-click the document in the file explorer to move it Working Files. Live preview will behave as expected when moving between files in getting started.

Version: sprint 39 experimental build 0.39.0-12914 (release b748891)
Windows 7 64-bit
Chrome Version: 34.0.1847.137 m