How to add a text-widget of a registered sidebar on wordpress' dashboard?

Question

I'm wondering if it is possible to add a specific text-widget($id) or either an entire dynamic_sidebar($id) in to the wordpress' dashboard.

Actually, I just need the client to edit the text of a text-widget on dashboard, without going to the menu "Appearance > Widgets" — this section is hidden for this user role.

If you can leave here some link or code, I'd appreciate it.
Thanks in advance

Answer 1

To solve this, my research led me to:

• Programmatically add widgets to sidebars
• How to use control_callback when creating a widget via functions.php or plugin?

The following is just a proof of concept based on the always excellent code of @Bainternet (in the Q about control_callback).

The Dashboard Widget displays the title of a selected Text Widget ^{it displays "Content of..." but should be "Title of..."}

Its configuration screen displays a dropdown with all Text Widgets of all Sidebars:

Here's the Appearance > Widgets screen

Now, what's left to implement is an editing interface (text input and so on) and save the proper values inside the option widget_text, using:
update_option('widget_text', $a_VERY_well_structured_array_otherwise_things_will_break);.

<?php
/*
Plugin Name: Dashboard Widget to deal with Text Widgets
Plugin URI: http://stackoverflow.com/q/14898302/1287812
Description: based on Bainternet plugin https://wordpress.stackexchange.com/q/77830/12615
Version: 0.1
Author: brasofilo
Author URI: https://wordpress.stackexchange.com/users/12615/brasofilo
*/

// Register widget
add_action( 'wp_dashboard_setup', 'add_dashboard_widget_wpse_77830' );

function add_dashboard_widget_wpse_77830() 
{
    wp_add_dashboard_widget(
        'dashboard_widget_wpse_77830', 
        'Text Widgets', 
        'dashboard_widget_wpse_77830', 
        'dashboard_widget_wpse_77830_handle'
    );
}

// Show widget
function dashboard_widget_wpse_77830() 
{
    //get saved data
    if ( !$widget_options = get_option( 'my_dashboard_widget_options' ) )
        $widget_options = array();

    $saved_txt_widget = isset( $widget_options['txt_widget'] ) ? $widget_options['txt_widget'] : '';
    echo "
    <p><strong>Content of the Widget</strong></p>
    <div class='txt_widget_class_wrap'>
        <label style='background:#ccc;'>&nbsp; {$saved_txt_widget}</label>
    </div>
    ";
}

// Configure and update widget
function dashboard_widget_wpse_77830_handle()
{

    // Get saved data
    if ( !$widget_options = get_option( 'my_dashboard_widget_options' ) )
        $widget_options = array();

    // Process update
    if ( 'POST' == $_SERVER['REQUEST_METHOD'] && isset($_POST['my_dashboard_widget_options']) ) 
    {
        // Minor validation
        $widget_options['txt_widget'] = wp_kses( $_POST['my_dashboard_widget_options']['txt_widget'], array() );
        // Save update
        update_option( 'my_dashboard_widget_options', $widget_options );
    }

    // Set defaults  
    if( !isset( $widget_options['txt_widget'] ) )
        $widget_options['txt_widget'] = ''; //you can set the default

    // Get Widget Text
    $txt = get_option( 'widget_text' );
    // Not necessary in the array
    unset($txt['_multiwidget']);

    // Start HTML
    echo "
    <p><strong>Available Text Widgets</strong></p>
    <div class='txt_widget_class_wrap'>
        <label>Title</label>
        <select name='my_dashboard_widget_options[txt_widget]' id='txt_widget'>";

    // Print options
    foreach( $txt as $t )
    {
        printf(
            '<option value="%s" %s>%s</option>',
            $t['title'],
            selected( $widget_options['txt_widget'], $t['title'], false ),
            $t['title']
            );

    }

    // End HTML
    echo "
           </select>
       </div>
       ";
}