Screen snapshots below.
1. Click on “Set featured Image” link in “Featured Image Box”
2. Select featured image (from Gallery, corresponds to first image below)
3. Set Featured Image (Corresponds to second image below. In the screenshot, you can see where the selected image is highlighted and checked.)
4. Featured Image displays in Featured Image Meta Box.(Corresponds to third image below). For my particular set-up, this is an improvement over 3.5-RC3-23047, because previously, a small “thumbnail” of the featured image would not display in the Featured Image Box. So, things are working better.
5. Update page. Featured Image does not display in body of the page, nor replace the header (the header is currently a big “shim”, plain white, 1000 X 250 pixels to ensure the rotating images are above the Search box areas). This is a change from my experience with the Featured Image in 3.42, in which the featured image would either show up in the body of the page/post, or replace the header if it was larger than the header.
Here’s an example of how that happened on another test site I did using 3.42. In this second example, there are two large graphics. The featured images are the ones on the bottom, rotating. (It just occurred to me, however, that a possible factor is that in the 3.42 example, the featured images are in posts and are made sticky; that might be a significant factor because this is a page, and I don’t have a “sticky” option in the pages.)