Enrico Sorcinelli

Taxonomies Sortable allow to sort non-hierarchical taxonomy terms associated to objects by drag&drop them on the administration interface.
<h3>Usage</h3>
Once the plugin is installed you can make a taxonomy sortable in the following ways:
<ul>
<li>Programmatically by adding <code>'sortable' => true</code> argument in <code>register_taxonomy()</code>.</li>
<li>Programmatically by using <code>taxonomies_sortable</code> filter below.</li>
<li>Using the Settings->Taxonomies Sortable administration screen by selecting non-hierarchical taxonomies you want to make sortable.</li>
</ul>
Note that making a taxonomy sortable, implicitly means also setting <code>sort => true</code> for that taxonomy.
<h3>Hooks</h3>
<code>taxonomies_sortable</code>
Filter allowing to programmatically set sortable taxonomies.
<pre><code>apply_filters( 'taxonomies_sortable', array $taxonomies )
</code></pre>
<code>taxonomies_sortable_admin_settings</code>
Filter allowing to display or not the plugin settings page in the administration.
<pre><code>apply_filters( 'taxonomies_sortable_admin_settings', boolean $display )
</code></pre>

Taxonomies Sortable

Allows to sort taxonomy terms associated to objects.

Kharis Sulistiyono

Dropdown hierarchical category in WordPress post write panel or editing screen. It makes the categories or taxonomies list in a better UI which enables show/hide toggle of child categories. It comes with plugin settings page where you can select in what custom post type(s) the dropdown UI will be applied to.
The idea comes from default WordPress hierarchial post categories which looks not good. Imagine that there are a lot of child categories. After selecting child category then publishing or updating a post, the arrangement seems not pretty — the child categories moved away from its parent. This plugin tackles that situation.

WP Dropdown Hierarchical Category UI

It makes the categories or taxonomies list in a better UI which enables show/hide toggle of child categories. Supports any custom post types.

Taxonomies Sortable vs WP Dropdown Hierarchical Category UI