I fully agree. I also think that the separate recipient tab are rather annoying, in particular, because I usually want to select the recipients before I write the text. Accessibility will also benefit if all inputs can be reached easily with the Tab key without the need to switch between different tabs.

also, in the recipient tab the "encrypt with passphrase" option is at the very bottom and so far away from the other options that it is easily overlooked, if the window is fullsized.

Another thing we noticed today is that the pgpOnly check that determines if S/MIME and PGP or only PGP is shown (The radio buttons at the top right corner) is done only at initialization. So if you import your first S/MIME certs it will still only offer PGP certs and no option to switch. Just as a note here instead of a different issue because it is mostly for testing but should be improved on an update.