This is a quick tip on how to use the Photoshop Navigator in a effective way for painting details;
1. Here is a screenshot of Photoshop with an image I'll be working on, and highlighted is the Navigator tab;
2. By dragging that tab, you can release it anywhere else outside that window;
3. Then, resize the window to make a maximum use of it as you prefer;
4. Now, just zoom in on the image, work the small details while you still see on the Navigator your whole composition in almost real-time updates.