Thunderbird 78.2.0

What's new in this version:

Changes:
- OpenPGP Key generation now disabled when there is no default mail account configured
- OpenPGP: Encrypt saved drafts when OpenPGP is enabled
- Twitter search removed
- Calendar: Event summary dialog is now themeable
- MailExtensions: Some APIs now use defineLazyPreferenceGetter in order to benefit from caching

Fixes:
- OpenPGP Key Manager search function did not work
- OpenPGP Key Properties dialog was sometimes too small
- OpenPGP: Encrypted email would not send if address contained uppercase characters
- OpenPGP: "Key ID" column could not be resized in Key Manage
- OpenPGP: Keys containing invalid UTF-8 strings could not be imported
- OpenPGP: Enable automatic signing for encrypted messages in additional scenarios
- Many more OpenPGP bug fixes and improvements
- IMAP fetch chunk size was always 65536 bytes
- Attachment corruption could occur when downloading large attachments from an IMAP server that supports chunking
- IMAP server capabilities were not rechecked after upgrading to SSL/TLS connection
- Message Composer: Order of attachments could not be modified using drag & drop
- Composing messages with a " width" font did not work
- Drag and drop of address book contacts did not work in some situations
- Address book migration failed when there was a dot in the file name
- Address book: "Always prefer display name over message header" was always checked when editing a contact
- Address book performance optimizations
- Dialog to add a new mail account from "Account Settings" did not open
- "Select All" (Ctrl+A) in message source did not work until focused with a mouse click
- Ctrl+scroll wheel not zooming in message reader
- Setting/changing a signature from a file lost when closing account settings
- Adaptive Junk Mail settings could not be disabled
- Message filter dialog fixes: Missing scrollbar, drop-down list not wide enough
- Various UX and theme improvements