For all who want to try to get the DDevExtensions Delphi IDE plugin to work with Delphi 10.4 can now clone the DDevExtensions git repository. It contains the project files for Delphi 10.2 and 10.3.   I'm not able to help with any Delphi 10.4 issues, so you are on your own.   GitHub repository: https://github.com/ahausladen/DDevExtensions