Enigmail - how to encrypt only part of the message?

When I confirmed my OpenPGP key on launchpad I got a mail from them, that was only partially encrypted with my key (only few paragraphs inside the message). Is it possible to encrypt only chosen part of the message with Enigmail? Or what would be the easiest way to accomplish it?

Added #1:

I found a pretty convenient way for producing ASCII armoured encrypted messages by using Nautilus interface (useful for ones that for some reason doesn't like to work with terminal). You need to install Nautilus-Actions Configuration Tool, and add there a script with a name eg. "Encrypt in ASCII" and parameters:

path: gpg

parameters: --batch -sear %x %f

The trick is that now you can create file, with extension that would be name of your recipient, you can then fill it with your message, right click it in Nautilus, choose "Encrypt in ASCII", and you will have encrypted ascii file which content you can (probably) just copy to your message.

But if anybody knows more convenient solution please share it.

Added #1B:

In the above case if you care more about security of your messages, It's worth to turning off invisible backup files that gedit creates every time, you create new document, or just remember to delete them.

The easiest way I know is to use command line:

gpg -ea filetobeencrypted

and then copying the ascii file in the mail message.

Without command line I don't know a more convenient solution to what Łukasz presented. I tried it and it seems to work. I would add a note to someone interested in the solution that while the gpg is run on batch mode it can not ask the confirmation of the recipient. In order to circumvent the error of missing confirmation the recipient key shall be certified by sender's own key, and the sender's key shall have ultimate trust.