Posts: category "Top Level" behavior is inconsistent with Pages "Top Level" UI

[lancewillett]

Steps to reproduce

1. Starting at URL: https://wordpress.com/page/example.wordpress.com
2. Create a new post, in the editor sidebar try to add a new category.
3. Next, create a new page and look in Page Attributes in the sidebar of the editor.

What I expected

The toggle for "Top Level" would be the same interaction and interface for each action.

What happened instead

Posts category form uses a checkbox; Pages uses a toggle.

Screenshots

#### Context / Source

Via a recent #dogfooding by @beaulebens

[rachelmcr]

Although there have been some changes to the sidebar and settings since the original report, this difference still exists:

As shown in the screenshot, in the post editor it's also possible to uncheck the category "Top Level" option, which then triggers a warning about a parent item being required. In the page editor, it isn't possible to manually toggle off the "Top Level" option — it automatically toggles off when a different page is selected as the parent, and toggling it on deselects any selected parent page.

[alisterscott]

Confirming the difference still exists.

[davewhitley]

Short answer: just make them both a toggle. That way you don't have to worry about error notices for an unchecked checkbox.

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Long answer: both versions are a frustration interaction.

For the checkbox version, why would you allow me to uncheck the box if I can't proceed without checking something? Notice how the button is disabled in this state. If you can't submit the form without selecting something, then the checkbox should be a radio button instead.

The toggle is also frustrating. You can't click on it if it's in the on state. This creates mistrust, and the UI appears broken to the user. When you select a radio button, the toggle changes without the user touching the toggle, causing confusion.

[shaunandrews]

Here's a quick mockup: