Effects are not available in headers and footers. Is that intentional or an oversight? I had a cool idea I wanted to try on a header with the backdrop filter.
Hi @JvP,
For this release we intentionally didn’t add them to Bars and Containers since there’s risk for it to conflict with the sticky bar implementation, and with how the fixed left/right bars have their positioning calculated. We’ve talked about doing some things like allowing Sections in Headers/Footers or at least adding Effects to containers. This cycle has definitely revealed some more opportunity to expand things but we haven’t explored what’s concretely possible just yet.
Oh yes, sections in headers and footers would be amazing. I hope you can make that, and effects, happen in the header and footer builders in the future 
This reminds me of an earlier discussion about having rows and columns inside of off canvas, modal, and navigation elements. I believe this was talked about months ago in this beta cycle though I can’t find it right now. Anyway, I hope this is still on the table for a future cycle since this would open up many new possibilities with these elements. You could very easily build native mega menu’s that way, how cool would that be! 
Modals/Dropdowns/Off Canvas with child element support is definitely a priority with native mega menus being one of the main use cases we have in mind. The new prefab element system (like dragging in one of the Posts) elements would help us make potentially complex arrangements like that more accessible as well. It would be awesome to just place a “Mega Menu” (or whatever title we call it) in a header and have all that setup.
Exactly! Good to know it’s going to happen.
Another use case would be a collapsible sidebar like YouTube has or you could put faceted search filters in an off canvas area on your shop pages. Plenty of cool things.
Definitely. We’re looking forward to charting the course ahead once we get this cycle wrapped up.