Fast toggle to show "Flagged as Deleted" Messages

[bes-internal]

Prerequisites

• I have searched for duplicate or closed feature requests
• I have searched for plugins that provide already provide the feature

Proposal

1. Add a quick toggle button to the main message list interface to show/hide messages flagged as deleted (maybe it should be a combined button with displaying new messages next to the search)

2. Ensure the button not syncing the current setting in Preferences > Server Settings > "Do not show deleted messages", that should show the default state.

Motivation and context

Currently, in Preferences > Server Settings > "Flag the message for deletion instead of delete", users can choose to flag messages for deletion, which hides them from the message list. This mode is needed to save the original message directory when restoring.

However, there is no convenient toggle in the main interface to quickly show or hide these flagged messages.
It would be useful to add a toggle button in the message list interface (next to existing filters or in the toolbar) to show or hide "Flagged as Deleted" messages, without having to navigate back to Preferences > Server Settings each time.

[pabzm]

Thank you for that suggestion! It sounds solid to me. I just wonder where another button should be sitting.

But that would be a discussion for an actual implementation. I guess us maintainers won't find the time to tackle this soon. Feel free to start working on it, if it's important to you.