Solved Thunderbird To: blank doesn't show cursor

When I open the Write (Compose) window to compose a new message, when I click in the TO: blank, there's no cursor, and I can't type in a name and address there. If I type a letter that's in an addresses/contacts entry, a drop-down appears and lets me choose the recipient, but that means in order to write to an address NOT in my address book, I'd have to enter that contact in my address book first. Then typing the name would bring it up.

The default behavior of the Write window is supposed to be to enter into my chosen address book the contact info of an address I send mail to that is NOT in my address book. Then, I suppose, I'm supposed to copy that to my main address if I wish, or delete it if I'm not going to use it again.

This is happening in both my 115.2 and my 118.0b2 TBirds.

It ain't impossible to do workarounds, but I shouldn't have to. Any idea how I can get my TO: blank to show a cursor again?

I am using 115.2.0 (Supernova) 64 bit TBird and I do not have this problem.

I am wondering if there is something corrupted in your installation? I know that using a write window does not always cause Windows to give that write window focus and show a cursor, but that doesn't seem to answer your question.

I guess what I am saying is that your situation is unusual, and TBird is not behaving normally. Sorry I couldn't help more.

It may be that you have put your finger on something. I’ll check the focus issue tomorrow.
Each of my versions is either a re-install or a successful update, so I think I’ll have to solve this without assuming there’s something wrong with the installation.
Late here. Bedtime. Tomorrow.

Solved with the expert support of @das10 on this forum. Again. I was a matter of revising the CSS file. See the thread Thunderbird 115: CSS Customization for details.