Add support for Position setting to Template Parts for Sticky Headers

[masperber]

Apologies if this is a duplicate issue. I searched for a related issue and couldn't find one.

The Group Block has a very useful setting called Position which allows you to Sticky it to the top of the page. It would be great if Template Parts--specifically the Header Template Part--had support for this setting.

What problem does this address?

Presently, if you want to make a template with a sticky header, you must encapsulate the header in a Group Block, and you cannot use the Header Template part.

What is your proposed solution?

Add support for the Position > Sticky setting to Template Parts, or at least the Header Template part.

I also suggest that it would be useful to add a Position > Bottom setting to the Footer template part.

[andrewserong]

Thanks for opening up this issue! Unfortunately it isn't a simple one to implement because of the confusion that can be created when opening up styling controls directly in the template part itself. I had a go at this previously in #47133 — the problem is that if you set the template part to sticky, it doesn't propagate across all instances of the template part, which can be confusing. And conversely, if we were to somehow get it to propagate by storing metadata somewhere, that also might not be the desired goal for the user.

The feedback on that PR was that it's better not to expose styling controls on template parts just yet (#47133 (comment)), until there's a more flexible way of controlling style values at the template part level, that factors in the local vs global problem for template parts.

Apologies if this is a duplicate issue. I searched for a related issue and couldn't find one.

I don't think there was a separate issue for this one, so thanks again for opening it. I'll link to it from the list of follow up tasks on the sticky position tracking issue: #47043

[mxhassani]

Another case here: 8988663-zen

[bradhogan]

Would love to see this added. I understand the concerns or difficulties, but it would be useful.