When did the problem start? Have you had the problem before?

About two weeks back - not related to update of any software.

Does it respond to clicks, if clicked in the body?

Cannot click in the body of the message or in the address line. Cursor simply disappears.

Do you have a mouse or a trackpad for clicking? I'm thinking it might be Thunderbird itself, did you try re adding your email account? Or reinstalling Thunderbird?

I use a Mac desktop with a mouse, hence no trackpad. Tried reinstalling Thunderbird several times, but it kept asking me if I wanted to replace it with an earlier version. Don't understand reference to adding my email account...

Did you try Earlybird at all? You can remove the account and re add it under local folders.

I know what Earlybird is, but I can't follow what you suggest...

Alright and my bad, so to re add an account, click on tools, then go down to account actions menu, click remove account. Then go to add account in local folders and re add the account from there. Let me know if it works.

Clicked on "tools"; no "account actions", so clicked on "account settings"; no "remove account" option; tried to open new account in same name; made no difference....

Alright, sounds like it's Thunderbird itself, will search some more for you, sorry what I suggested didn't work for you.

and the account actions is in the account settings, bottom left.

Yes, it is, but "remove account" is faded out and cannot be clicked.

Nothing seems to help, so I'll just have to move to another program. Thanks for your efforts!