Handling admin pages with tables

This is a terrible idea. There is no such thing as "not mobile content". If you want to hide this from small viewports, ask the following question: do we really need it for the large viewports. If we need it for large viewports, we should not hide it just because someone is on a smaller viewports. There are a plethora of responsive table solutions, we should implement one of them (or come up with our own) before we start willy-nilly hiding columns for small viewports.

This is the direction that has already been implemented in core. See the patch commited #1276908: Administrative tables are too wide for smaller screens

Added admin/people/roles

Here's a issue to unify code for draggable admin listings #1855402: Add generic weighting (tabledrag) support for config entities (DraggableListController)

Edited no of columns

We can try to hide extra data in the existing tables that Drupal core produces in the Admin UI, but let's not forget that Drupal is built to be extensible.

If a site builder creates a table View for administrators, to replace or augment an existing admin page like /admin/content/content, and the Seven theme's layout completely *breaks* on this page, is it the sitebuilder's fault? IMHO, it's the theme's responsibility to support the fundamental issue of too much data in a row (or header) to fit into a narrow screen.

The obvious solution for this scenario is to add a wrapper around the view table, that denotes that the view is a table layout (this currently doesn't exist), and use overflow-y: scroll; on that wrapper. Then you come to the problem of keeping sticky headers in sync as you scroll horizontally. -- for me the solution here is also easy: simply don't allow sticky headers when the table header width is wider than the viewport width.

Thoughts?

Answering my own question, it looks like views already supports Responsive Tables #1796230: Support responsive tables based on the Filament Group's solution.

So with that in mind, where does this issue now stand?

Let's work with the assumption that not every admin table will become a view. Let's finish implementing what we started in #1276908: Administrative tables are too wide for smaller screens

The obvious solution for this scenario is to add a wrapper around the view table, that denotes that the view is a table layout (this currently doesn't exist), and use overflow-y: scroll; on that wrapper.

Sadly that is not an adequate solution either, testing showed that it's incredibly difficult to keep track of which row is the one you want when scrolling horizontally.

Ok I've applied the table solution to

admin/config/content/formats
admin/config/regional/date-time

I was going to do the others but I'm really struggling to find out where these are kept. Can someone drop me a hint with admin/config/people/accounts/field?

Related #1876712: [meta] Convert all tables in core to new #type 'table'

We need to solve common trouble with tables in core #1876718: Allow modules to inject columns into tables more easily
So making columns and easy alterable

Related: #1975352: Wide table can push table wider than viewport

Retain first & last column, hide other columns by default on narrow screens for: admin/config/content/formats & admin/config/regional/date-time

It feels like this was succeeded by #2280035: Add another responsive tables solution that doesn't hide content. Feel free to reopen though.