Allow associative arrays in theme settings values.

[IPBaddons]

Now, system prevents me from using Stack field type with Key/Value in theme settings by last line in below code:

system/Theme/Theme.php line 2022

$save = array();
$json = array();
foreach( $themeSettings as $settingId => $row )
    {
        if ( array_key_exists( "core_theme_setting_title_{$row['sc_id']}", $values ) )
            {
                $field       = $this->getCustomSettingField( $row, TRUE );
                $stringValue = $field::stringValue( $values["core_theme_setting_title_{$row['sc_id']}"] ); // THIS
					

If we use \Form\Stack with Key Value we get associative array, and stringValue doesn't consider this case.

Array, Array, Array,

same issue here: 

Is this possible?