WP: hack to keep the Block library/Inserter open unless manually closed.

block-library-disdialoged.php

<?php
/**
 * Plugin Name:       Block Library Disdialoged
 * Description:       Hack to keep the Block library/Inserter open unless manually closed.
 * Version:           0.2.0
 * License:           GPL-2.0-or-later
 */

add_action( 'admin_footer', function() {
	// Bails unless on a block editor screen
	if ( ! get_current_screen()->is_block_editor() ) return;

	?>
	<script>
		const ogHasFocus = document.__proto__.hasFocus;
		document.addEventListener('focusout', e => {
			const wasWithinInserter = !! e.target?.closest('[aria-label="Block Library"]');
			if ( wasWithinInserter )
				document.__proto__.hasFocus = () => {
					document.__proto__.hasFocus = ogHasFocus;
					return false;
				}
		})
	</script>
	<?php
}, 1000);