I don't know if this is just common knowledge, which it actually may be if people actually read the manual, but I just discovered it today while looking something up in the manual. If you click the Area Render button, it will glow red. This will let you know it is initialized and ready to use. You can then drag a box within the Preview window. The render engine will then use your most current render settings to render just the area you boxed in! I have been using it all day to adjust small parts of my scene, then see if the changes worked the way I planned. I have the Firefly settings all the way up to production, but it runs good and fast, since I am only rendering a small section at a time. If this is nothing big, then sorry about the post. But I read the P5 manual cover to cover when I got it. I didn't bother reading the P6 manual since I only got the DL edition, and reading a 300-something page PDF is not high on my list of fun things to do. I don't remember this feature being available in past, though I may be wrong. I would never have even tried it if I didn't read it by accident, and if there is anyone else who could benefit then I am glad I posted.