Can we remove Bartik 1.20.0 Legacy front-end theme

[domaingood]

Can we remove Bartik 1.20.0 Legacy front-end theme from core? Also Zen is a modern, powerful, HTML5 starting theme with component-based CSS and a responsive, mobile-first grid design. Add Zen in Backdrop Core

[stpaultim]

@domaingood - I don't have strong attachments to having Bartik in core. But, I'm pretty sure that this would have to be a 2.0 issue.

I don't think that we can remove something like Bartik without potentially breaking existing sites. I will assume that another reason for having it in core is to facilitate easy upgrades for the many Drupal 7 sites that are using it. It is a part of Drupal 7 core.

Also Zen is a modern, powerful, HTML5 starting theme with component-based CSS and a responsive, mobile-first grid design. Add Zen in Backdrop Core

I think that this should be a separate issue.

There is also an open discussion about adding a new theme to core.
#5175

[klonos]

Now with #285 in core, we should start gathering metrics re enabled/used themes (#5186). That should help us make better-informed decisions.

But yes, although we could add a new core theme, removing an existing core theme would be a task for Backdrop 2.x (not before Jan 2025).

[jenlampton]

It's imoportant to note that Bartik is important for the upgrade path from Blocks to Layouts. If your blocks were placed in regions in the Bartik theme in Drupal 7, they got placed into equivalent regions in the Simmons layout in Backdrop core. If we remove the Bartik theme, we may also choose to remove the Simmons Layout, and if so, we'll need to re-write that upgrade path.

The first thing that comes to mind is that we could use a Flexible layout that resembles Bartik in these cases, instead of Simmons.

[olafgrabienski]

In case we remove a theme from Backdrop core, people should be able to continue using the theme on their existing site. Did we already discuss somewhere how to achieve that?

edit: I'm asking also with base themes in mind: How can people continue to use a base theme for their custom theme?

[stpaultim]

I don't know if it's the best option, but we did discuss that if we removed any modules or themes from core, we would make them available as contrib modules.

I would hope that if we did this, we could put an alert in the upgrade process that let anyone know if they have Bartik enabled, what they need to do.