Cameron Jones

Fluid Customizer is a simple plug-and-play plugin which allows you to resize the width of the preview window in the Customizer to whichever size you like. Simply install the plugin, go to your Customizer, then click and drag the right border of the sidebar and watch the magic happen!

Fluid Customizer

Preview your site for a variety of different devices by resizing your Customizer sidebar with a simple click and drag

Weston Ruter

This plugin adds a Customizer control to select one or multiple posts (and eventually terms and users).
Core has long had a <code>dropdown-pages</code> control type which is used in the static front page section for the “page on front” and “page for posts” controls. There is a problem with this control however: it outputs the entire tree of pages for every registered instance of the control. For sites that have a lot of pages, this can introduce a performance problem to generate this full list, not only once, but twice for the two controls. This plugin upgrades the “page on front” and “page for posts” controls to instead make use of the Customize Object Selector control, not only allowing for the list of pages to be loaded via Ajax on demand but also for the list to be searched.
When the <a href="https://github.com/xwp/wp-customize-posts" rel="nofollow ugc">Customize Posts</a> plugin is active, buttons will appear after the Select2 control to be able to create new posts to add to the selection. The Customize Object Selector will also power the post parent control. See <a href="https://github.com/xwp/wp-customize-posts/pull/233" rel="nofollow ugc">wp-customize-posts#233</a>.
This plugin also includes a reusable JavaScript component available at <code>wp.customize.ObjectSelectorComponent</code> which can be used in widgets or other locations.
For an example integration with widgets, see the <a href="https://github.com/xwp/wp-js-widgets/pull/10" rel="nofollow ugc">Post Collection widget</a>.
For an example integration with the Customize Posts plugin, see pending usage as the <a href="https://github.com/xwp/wp-customize-posts/pull/189#issuecomment-241216247" rel="nofollow ugc">Post Parent control</a>.
Development of this plugin is done <a href="https://github.com/xwp/wp-customize-object-selector" rel="nofollow ugc">on GitHub</a>. Pull requests welcome. Please see <a href="https://github.com/xwp/wp-customize-object-selector/issues" rel="nofollow ugc">issues</a> reported there before going to the <a href="https://wordpress.org/support/plugin/customize-object-selector" rel="ugc">plugin forum</a>.

Customize Object Selector

Adds a Customizer control to select one or multiple posts (and eventually terms and users).

Fluid Customizer vs Customize Object Selector