The way you use jQuery in the HTML tab isn’t working any more. Sure you are able to use jQuery there when done correctly.
Yes, you can use window.onload, or do there exists an other possibility? And if yes, which one?
Don’t use window onLoad. That event might be to late. I would use: Window: DOMContentLoaded event - Web APIs | MDN
Thank you very much, learned something new today 
While evaluating Blocs as a website builder application @Norm, @MDS, @Blocs_User, and after @Whittfield suggested custom brics as way to create new functionality in blocs. Therefore, I was wondering if custom brics support creating expandable sections in the “Inspector” for custom brics? 
You can add options to the sidebar of your custom bric, but they aren’t expandable. But this would be a great feature to add.
Thank you for your reply! @Whittfield
I would like to create custom brics with the same features and functionality as original brics; i.e. expandable sections inside “Inspector” @norm Does this mean I need the ability to create/extend the list of interfaces when using “Bric Builder”?
This is, obviously, a very old thread and the video has long since been deleted, but I can find nothing more recent. The documentation is, I’m sure, adequate if you are already a full-stack webdev, but as someone learning as they go, it’s still too opaque.
Does anyone know of any video/tutorial/example of creating custom brics from idea to extension manager availability?