We've lamented the squanderous allocation of Thunderbird resources before, so here is the next installment.
This mailing list post just hit the so-called Thunderbird UX mailing list. They author announces a redesign with the aim to simplify the Calendar UI, amongst other things. So what they have done is actually to remove functionality. But they author of the article preempts any concern by stating (quote):
These changes will be completely optional, kept in a separate “New Calendar” space, so those who need legacy features won’t lost access to any of their workflows.
How useful, so the rework will either be hidden, or users will hide it to get the functionality back that they need.
Thunderbird DOES NOT NEED yet another redesign and refactoring, what it needs is that the 2,538 open Calendar bugs be properly triaged and the most important ones fixed, like these:
| Bug | Open since (Votes) |
|---|---|
| Subtasks | 2003 (70) |
| Birthdays from address book | 2002 (54) |
| RFC-compliant alarms | 2011 |
| Invitation mail processing | 2009 (33) |
| Lots of CalDAV issues, examples: Bug 1439379 - Bug 1694709 - Bug 1713625 - Bug 1848949 |
|
| Daytime Saving Transitions | Priority 1 |
| Outlook interoperability | (fixed in Betterbird) |
| Spellcheck | 2022 (fixed in Betterbird) |
Full list here, sort by Votes.
The Calendar component has been mostly abandoned since its Module Owner has moved onto greener pastures in so-called Thunderbird services (Thundermail, etc.). So now, instead of providing real functionality improvements, the Thunderbird folks have switched to polishing the turds.

