Marko - Thanks for your reply. On my computers, the window I get when I press "d" is the same centered, partial window I was complaining about. Michael's tip on pressing Shift while opening that window (the one you get when pressing "d"
while clicking the double headed arrow of that partial window) brings up a new screen which is the full size of the computer screen.
This morning, they've apparently restored the ability to scale inserted images, even in the "d" window. It was always possible to do this in the past, but yesterday it was impossible. Now, it's a little more difficult, but it can be done in the smaller centralized compose window as well as the full-screen one.
In case you're interested, here's how to scale images:
The image used to open up in the compose window at about half the size of the compose window. Now it opens at the full size of the compose window, but scaling it down works the same as it did in the past. Clicking on the lower right corner of the image brings up boundary markings (small squares on corners and in the centers of the sides, top, and bottom of the image). After the boundary markings show, clicking on the lower right corner allows me to scale the image down and/or to change its aspect ratio, by pushing the boundary marker up and to the right (to decrease size of the image). With this "new" setup, I have to be careful to avoid a new sliding "elevator bar" at the right of the image - but with a little care, it works just fine.
The older way of opening the image at half the size of the compose window worked a little more easily - but this new way works fine. I'm happy again.
Bill