Add the WindowListener API to the extension manifest. This will cause the extension to ignore the chrome.manifest file.
There is a possibility that Clippings will be broken after this is done, due to the usage of RDF as the data store and the uncertainty as to whether the RDF templates for dynamically building the XUL context menu items and the Clippings Manager tree list will still be functional.
This is the second part of an attempt to port Clippings for Thunderbird to Thunderbird 78, keeping the XUL-based code and making modifications to accommodate the changes to XUL support in Thunderbird 78. I am following this tutorial: https://github.com/thundernest/addon-developer-support/wiki/Using-the-WindowListener-API-to-convert-a-Legacy-Overlay-WebExtension-into-a-MailExtension-for-Thunderbird-78
Add the WindowListener API to the extension manifest. This will cause the extension to ignore the chrome.manifest file.
There is a possibility that Clippings will be broken after this is done, due to the usage of RDF as the data store and the uncertainty as to whether the RDF templates for dynamically building the XUL context menu items and the Clippings Manager tree list will still be functional.