Better way to handle WordPress Dashboard widgets with options

jQuery(function($){

	// the Configure link click event
	$('#misha_dashboard_widget .edit-box.open-box').click(function(){
		var button = $(this);
		$.ajax({
			url: ajaxurl, // it is predefined in /wp-admin/
			type: 'POST',
			data: 'action=showform',
			beforeSend : function( xhr ){
				// add preloader
				button.hide().before('<span class="spinner" style="visibility:visible;display:block;margin:0 0 0 15px"></span>');
			},
			success : function( data ){
				// remove preloader
				button.prev().remove();
				// insert settings form
				$('#misha_dashboard_widget').find('.inside').html(data);
			}

		});
		return false;
	});
		
	// form submit event
	$('body').on('submit', '#misha_widget_settings', function(){
		var form = $(this);
		$.ajax({
			url: ajaxurl,
			type: 'POST',
			data: $(this).serialize(), // all form fields
			beforeSend : function( xhr ){
				// add preloader just after the submit button
				form.find('.submit').append('<span class="spinner" style="display:inline-block;float:none;visibility:visible;margin:0 0 0 15px"></span>');
			},
			success : function( data ){
				$('#misha_dashboard_widget').find('.inside').html(data);
				// show the Configure link again
				$('#misha_dashboard_widget .edit-box.open-box').show();
			}
		});
		return false;
	});
});

/*
 * This action hook shows settings form
 */
add_action( 'wp_ajax_showform', 'misha_ajax_show_form' ); // wp_ajax_{ACTION}
function misha_ajax_show_form(){

	// widget ID should match but it is not required
	$widget_id = 'misha_dashboard_widget';

	echo '<form method="post" id="misha_widget_settings">
	<h3>Select a page that will be displayed in widget</h3>'
	. wp_dropdown_pages( array(
		'post_type' => 'page',
		'selected' => get_option( 'custom_post' ),
		'name' => 'my_custom_post',
		'id' => 'my_custom_post',
		'show_option_none' => '- Select -',
		'echo' => false
	) )
	. '<input type="hidden" name="action" value="widgetsave" /><input type="hidden" name="widget_id" value="' . $widget_id . '">'
	. wp_nonce_field( 'edit-dashboard-widget_' . $widget_id, 'dashboard-widget-nonce', true, false )
	. '<p class="submit"><input type="submit" name="submit" id="submit" style="display:inline-block" class="button button-primary" value="Submit"></p></form>';

	die;
}

/*
 * This action hook saves the settings and displays the widget content
 */
add_action( 'wp_ajax_widgetsave', 'misha_save_widget' ); // wp_ajax_{ACTION}
function misha_save_widget(){

	// security check
	check_ajax_referer( 'edit-dashboard-widget_' . $_POST['widget_id'], 'dashboard-widget-nonce' );

	$post_id = absint( $_POST['my_custom_post'] );
	
	update_option( 'custom_post', $post_id );

	if( $post = get_post( $post_id ) ) {
		$c = do_shortcode( html_entity_decode( $post->post_content ) );
		echo "<h2>{$post->post_title}</h2><p>{$c}</p>";
	} else {
		echo 'Widget is not configured.';
	}
	
	die;
}