WordPress has a nice editor, with which are several hundreds of articles written daily.

But in my opinion the editor has an usability issue.
Every time you save a post the scroll position of the editor will be on top again. If you want to continue writing the post you have first to find he old position again. This can be time-consuming.

Save editor scroll position on saving

To avoid this behavior I have written a snippet which I want to share now with you.

<?php
/**
 * The class will help you to recover the old scoll position in your Editor.
 * Either HTML or visuel editor.
 */
final class Preserve_Editor_Scroll_Position {
        /**
         * Init
         */
        public static function init() {
                add_filter( 'redirect_post_location', array( __CLASS__, 'add_query_arg' ) );
                add_action( 'edit_form_advanced', array( __CLASS__, 'add_input_field' ) );
                add_action( 'edit_page_form', array( __CLASS__, 'add_input_field' ) );
                add_filter( 'tiny_mce_before_init', array( __CLASS__, 'extend_tiny_mce' ) );
        }
        /**
         * Adds a hidden input field for scrolltop value
         */
        public static function add_input_field() {
                $position = ! empty( $_GET['scrollto'] ) ? $_GET['scrollto'] : 0;
                printf( '<input type="hidden" id="scrollto" name="scrollto" value="%d"/>', esc_attr( $position ) );
                // Print Javascript data
                add_action( 'admin_print_footer_scripts', array( __CLASS__, 'print_js' ), 55 ); // Print after Editor JS.
        }
        /**
         * Extend TinyMCE config with a setup function
         */
        public static function extend_tiny_mce( $init ) {
                if ( 'tinymce' == wp_default_editor() )
                        $init['setup'] = 'rich_scroll';
                return $init;
        }
        /**
         * Returns redirect url with query arg for scroll position
         */
        public static function add_query_arg( $location ) {
                if ( ! empty( $_POST['scrollto'] ) )
                        $location = add_query_arg( 'scrollto', (int) $_POST['scrollto'], $location );
                return $location;
        }
        /**
         * Prints Javascript data
         */
        public static function print_js() {
                ?>
        <script>
        ( function( $ ) {
                $( '#post' ).submit( function() {
                        scrollto =
                                $( '#content' ).is( ':hidden' ) ?
                                $( '#content_ifr' ).contents().find( 'body' ).scrollTop() :
                                $( '#content' ).scrollTop();
                        $( '#scrollto' ).val( scrollto );
                } );
                $( '#content' ).scrollTop( $( '#scrollto' ).val() );
        } )( jQuery );
        function rich_scroll( ed ) {
                ed.onInit.add( function() {
                        jQuery( '#content_ifr' ).contents().find( 'body' ).scrollTop( jQuery( '#scrollto' ).val() );
                } );
        };
        </script>
                <?php
        }
}
add_action( 'plugins_loaded', array( 'Preserve_Editor_Scroll_Position', 'init' ) );

If you want you can create your own plugin with this snippet or you can download the plugin Preserve Editor Scroll Position.