It is unsafe to write confidential text in a web browser since JavaScript attacks can access it from inside the browser. You should rather write your text in a separate application, encrypt it using OpenPGP Applet, and paste the encrypted text in your browser, before sending it by email for example.

When using OpenPGP Applet to encrypt emails, non-ASCII characters (for example non-Latin characters or characters with accents) might not display correctly to the recipients of the email.

If you are going to encrypt emails often, we recommend you to set up Thunderbird instead.