# Page Not Found

The URL `add-ons/tb68/overlays` does not exist.

You might be looking for one of these pages:
- [Convert legacy overlay extension to legacy WebExtension](https://developer.thunderbird.net/add-ons/updating/historical-overview/overlays.md)
- [Introducing Experiments](https://developer.thunderbird.net/add-ons/mailextensions/experiments.md)
- [Documentation & Resources](https://developer.thunderbird.net/add-ons/resources.md)
- [Introduction](https://developer.thunderbird.net/add-ons/about-add-ons.md)
- [How to convert legacy extensions?](https://developer.thunderbird.net/add-ons/updating/historical-overview.md)

## How to find the correct page

1. **Browse the full index**: [/sitemap.md](https://developer.thunderbird.net/sitemap.md) - Complete documentation index
2. **View the full content**: [/llms-full.txt](https://developer.thunderbird.net/llms-full.txt) - Full content export

## Tips for requesting documentation

- For markdown responses, append `.md` to URLs (e.g., `/add-ons/updating/historical-overview/overlays.md`)
- Use `Accept: text/markdown` header for content negotiation