>FWIW I'm seeing the same behaviour as Al and Sergey. In addition:

I will take a look at it today.

>Clicking the 'Preview'' button on a reply show two copies of the message.

What it shows is a preview at the bottom. But, your edit text is still on top. So, you are still on the same page and can continue to update as desire, preview as often as you like and save when you are ready to send the message.