diff --git a/libraries/common.lib.php b/libraries/common.lib.php
index 6c53abf628..5ffca0375a 100644
--- a/libraries/common.lib.php
+++ b/libraries/common.lib.php
@@ -3091,7 +3091,7 @@ function PMA_replaceBinaryContents($content)
  * @param binary $data        GIS data
  * @param bool   $includeSRID Add SRID to the WKT
  *
- * @return GIS data in Well Know Text format
+ * @return string GIS data in Well Know Text format
  */
 function PMA_asWKT($data, $includeSRID = false)
 {
@@ -3516,7 +3516,7 @@ function PMA_getGISDatatypes($upper_case = false)
  *
  * @param string $gis_string GIS string
  *
- * @return GIS data enclosed in 'GeomFromText' function
+ * @return string GIS data enclosed in 'GeomFromText' function
  */
 function PMA_createGISData($gis_string)
 {
diff --git a/libraries/config/ConfigFile.class.php b/libraries/config/ConfigFile.class.php
index 64bc72d7f4..ea19fbd5b0 100644
--- a/libraries/config/ConfigFile.class.php
+++ b/libraries/config/ConfigFile.class.php
@@ -18,45 +18,45 @@ class ConfigFile
      * Stores default PMA config from config.default.php
      * @var array
      */
-    private $cfg;
+    private $_cfg;
 
     /**
      * Stores original PMA_Config object, not modified by user preferences
      * @var PMA_Config
      */
-    private $orgCfgObject;
+    private $_orgCfgObject;
 
     /**
      * Stores allowed values for non-standard fields
      * @var array
      */
-    private $cfgDb;
+    private $_cfgDb;
 
     /**
      * Keys which will be always written to config file
      * @var array
      */
-    private $persistKeys = array();
+    private $_persistKeys = array();
 
     /**
      * Changes keys while updating config in {@link updateWithGlobalConfig()}
      * or reading by {@link getConfig()} or {@link getConfigArray()}
      * @var array
      */
-    private $cfgUpdateReadMapping = array();
+    private $_cfgUpdateReadMapping = array();
 
     /**
      * Key filter for {@link set()}
      * @var array|null
      */
-    private $setFilter;
+    private $_setFilter;
 
     /**
      * Instance id (key in $_SESSION array, separate for each server -
      * ConfigFile{server id})
      * @var string
      */
-    private $id;
+    private $_id;
 
     /**
      * Result for {@link _flattenArray()}
@@ -77,15 +77,15 @@ class ConfigFile
     private function __construct()
     {
         // load default config values
-        $cfg = &$this->cfg;
+        $cfg = &$this->_cfg;
         include './libraries/config.default.php';
         $cfg['fontsize'] = '82%';
 
         // create PMA_Config to read config.inc.php values
-        $this->orgCfgObject = new PMA_Config(CONFIG_FILE);
+        $this->_orgCfgObject = new PMA_Config(CONFIG_FILE);
 
         // load additional config information
-        $cfg_db = &$this->cfgDb;
+        $cfg_db = &$this->_cfgDb;
         include './libraries/config.values.php';
 
         // apply default values overrides
@@ -95,9 +95,9 @@ class ConfigFile
             }
         }
 
-        $this->id = 'ConfigFile' . $GLOBALS['server'];
-        if (!isset($_SESSION[$this->id])) {
-            $_SESSION[$this->id] = array();
+        $this->_id = 'ConfigFile' . $GLOBALS['server'];
+        if (!isset($_SESSION[$this->_id])) {
+            $_SESSION[$this->_id] = array();
         }
     }
 
@@ -121,7 +121,7 @@ class ConfigFile
      */
     public function getOrgConfigObj()
     {
-        return $this->orgCfgObject;
+        return $this->_orgCfgObject;
     }
 
     /**
@@ -129,12 +129,14 @@ class ConfigFile
      * they are set to their default values (use only full paths)
      *
      * @param array $keys
+     *
+     * @return void
      */
     public function setPersistKeys($keys)
     {
         // checking key presence is much faster than searching so move values
         // to keys
-        $this->persistKeys = array_flip($keys);
+        $this->_persistKeys = array_flip($keys);
     }
 
     /**
@@ -144,7 +146,7 @@ class ConfigFile
      */
     public function getPersistKeysMap()
     {
-        return $this->persistKeys;
+        return $this->_persistKeys;
     }
 
     /**
@@ -152,45 +154,54 @@ class ConfigFile
      * this method to set up a filter on {@link set()} method
      *
      * @param array|null $keys array of allowed keys or null to remove filter
+     *
+     * @return void
      */
     public function setAllowedKeys($keys)
     {
         if ($keys === null) {
-            $this->setFilter = null;
+            $this->_setFilter = null;
             return;
         }
         // checking key presence is much faster than searching so move values
         // to keys
-        $this->setFilter = array_flip($keys);
+        $this->_setFilter = array_flip($keys);
     }
 
     /**
      * Sets path mapping for updating config in
      * {@link updateWithGlobalConfig()} or reading
      * by {@link getConfig()} or {@link getConfigArray()}
-     * @var array
+     *
+     * @param array $mapping
+     *
+     * @return void
      */
     public function setCfgUpdateReadMapping(array $mapping)
     {
-        $this->cfgUpdateReadMapping = $mapping;
+        $this->_cfgUpdateReadMapping = $mapping;
     }
 
     /**
      * Resets configuration data
+     *
+     * @return void
      */
     public function resetConfigData()
     {
-        $_SESSION[$this->id] = array();
+        $_SESSION[$this->_id] = array();
     }
 
     /**
      * Sets configuration data (overrides old data)
      *
      * @param array $cfg
+     *
+     * @return void
      */
     public function setConfigData(array $cfg)
     {
-        $_SESSION[$this->id] = $cfg;
+        $_SESSION[$this->_id] = $cfg;
     }
 
     /**
@@ -199,6 +210,8 @@ class ConfigFile
      * @param string $path
      * @param mixed  $value
      * @param string $canonical_path
+     *
+     * @return void
      */
     public function set($path, $value, $canonical_path = null)
     {
@@ -206,30 +219,32 @@ class ConfigFile
             $canonical_path = $this->getCanonicalPath($path);
         }
         // apply key whitelist
-        if ($this->setFilter !== null && !isset($this->setFilter[$canonical_path])) {
+        if ($this->_setFilter !== null
+            && ! isset($this->_setFilter[$canonical_path])
+        ) {
             return;
         }
         // remove if the path isn't protected and it's empty or has a default
         // value
-        if (!isset($this->persistKeys[$canonical_path])) {
+        if (!isset($this->_persistKeys[$canonical_path])) {
             $default_value = $this->getDefault($canonical_path);
             // we need original config values not overwritten by user
             // preferences to allow for overwriting options set in
             // config.inc.php with default values
             $instance_default_value = PMA_array_read(
                 $canonical_path,
-                $this->orgCfgObject->settings
+                $this->_orgCfgObject->settings
             );
             if (($value === $default_value && (defined('PMA_SETUP')
                 || $instance_default_value === $default_value))
                 || (empty($value) && empty($default_value) && (defined('PMA_SETUP')
                 || empty($current_global)))
             ) {
-                PMA_array_remove($path, $_SESSION[$this->id]);
+                PMA_array_remove($path, $_SESSION[$this->_id]);
                 return;
             }
         }
-        PMA_array_write($path, $_SESSION[$this->id], $value);
+        PMA_array_write($path, $_SESSION[$this->_id], $value);
     }
 
     /**
@@ -240,6 +255,8 @@ class ConfigFile
      * @param mixed $value
      * @param mixed $key
      * @param mixed $prefix
+     *
+     * @return void
      */
     private function _flattenArray($value, $key, $prefix)
     {
@@ -260,7 +277,7 @@ class ConfigFile
     public function getFlatDefaultConfig()
     {
         $this->_flattenArrayResult = array();
-        array_walk($this->cfg, array($this, '_flattenArray'), '');
+        array_walk($this->_cfg, array($this, '_flattenArray'), '');
         $flat_cfg = $this->_flattenArrayResult;
         $this->_flattenArrayResult = null;
         return $flat_cfg;
@@ -271,6 +288,8 @@ class ConfigFile
      * (config will contain differences to defaults from config.defaults.php).
      *
      * @param array $cfg
+     *
+     * @return void
      */
     public function updateWithGlobalConfig(array $cfg)
     {
@@ -284,8 +303,8 @@ class ConfigFile
         // should be complemented by code reading from generated config
         // to perform inverse mapping
         foreach ($flat_cfg as $path => $value) {
-            if (isset($this->cfgUpdateReadMapping[$path])) {
-                $path = $this->cfgUpdateReadMapping[$path];
+            if (isset($this->_cfgUpdateReadMapping[$path])) {
+                $path = $this->_cfgUpdateReadMapping[$path];
             }
             $this->set($path, $value, $path);
         }
@@ -301,7 +320,7 @@ class ConfigFile
      */
     public function get($path, $default = null)
     {
-        return PMA_array_read($path, $_SESSION[$this->id], $default);
+        return PMA_array_read($path, $_SESSION[$this->_id], $default);
     }
 
     /**
@@ -316,7 +335,7 @@ class ConfigFile
      */
     public function getDefault($canonical_path, $default = null)
     {
-        return PMA_array_read($canonical_path, $this->cfg, $default);
+        return PMA_array_read($canonical_path, $this->_cfg, $default);
     }
 
     /**
@@ -330,7 +349,7 @@ class ConfigFile
      */
     public function getValue($path, $default = null)
     {
-        $v = PMA_array_read($path, $_SESSION[$this->id], null);
+        $v = PMA_array_read($path, $_SESSION[$this->_id], null);
         if ($v !== null) {
             return $v;
         }
@@ -360,7 +379,7 @@ class ConfigFile
      */
     public function getDbEntry($path, $default = null)
     {
-        return PMA_array_read($path, $this->cfgDb, $default);
+        return PMA_array_read($path, $this->_cfgDb, $default);
     }
 
     /**
@@ -370,8 +389,8 @@ class ConfigFile
      */
     public function getServerCount()
     {
-        return isset($_SESSION[$this->id]['Servers'])
-            ? count($_SESSION[$this->id]['Servers'])
+        return isset($_SESSION[$this->_id]['Servers'])
+            ? count($_SESSION[$this->_id]['Servers'])
             : 0;
     }
 
@@ -382,9 +401,9 @@ class ConfigFile
      */
     public function getServers()
     {
-      return isset($_SESSION[$this->id]['Servers'])
-          ? $_SESSION[$this->id]['Servers']
-          : null;
+        return isset($_SESSION[$this->_id]['Servers'])
+            ? $_SESSION[$this->_id]['Servers']
+            : null;
     }
 
     /**
@@ -396,7 +415,7 @@ class ConfigFile
      */
     function getServerDSN($server)
     {
-        if (!isset($_SESSION[$this->id]['Servers'][$server])) {
+        if (!isset($_SESSION[$this->_id]['Servers'][$server])) {
             return '';
         }
 
@@ -430,7 +449,7 @@ class ConfigFile
      */
     public function getServerName($id)
     {
-        if (!isset($_SESSION[$this->id]['Servers'][$id])) {
+        if (!isset($_SESSION[$this->_id]['Servers'][$id])) {
             return '';
         }
         $verbose = $this->get("Servers/$id/verbose");
@@ -445,24 +464,26 @@ class ConfigFile
      * Removes server
      *
      * @param int $server
+     *
+     * @return void
      */
     public function removeServer($server)
     {
-        if (!isset($_SESSION[$this->id]['Servers'][$server])) {
+        if (!isset($_SESSION[$this->_id]['Servers'][$server])) {
             return;
         }
         $last_server = $this->getServerCount();
 
         for ($i = $server; $i < $last_server; $i++) {
-            $_SESSION[$this->id]['Servers'][$i]
-                = $_SESSION[$this->id]['Servers'][$i + 1];
+            $_SESSION[$this->_id]['Servers'][$i]
+                = $_SESSION[$this->_id]['Servers'][$i + 1];
         }
-        unset($_SESSION[$this->id]['Servers'][$last_server]);
+        unset($_SESSION[$this->_id]['Servers'][$last_server]);
 
-        if (isset($_SESSION[$this->id]['ServerDefault'])
-            && $_SESSION[$this->id]['ServerDefault'] >= 0
+        if (isset($_SESSION[$this->_id]['ServerDefault'])
+            && $_SESSION[$this->_id]['ServerDefault'] >= 0
         ) {
-            unset($_SESSION[$this->id]['ServerDefault']);
+            unset($_SESSION[$this->_id]['ServerDefault']);
         }
     }
 
@@ -488,8 +509,8 @@ class ConfigFile
      */
     public function getConfig()
     {
-        $c = $_SESSION[$this->id];
-        foreach ($this->cfgUpdateReadMapping as $map_to => $map_from) {
+        $c = $_SESSION[$this->_id];
+        foreach ($this->_cfgUpdateReadMapping as $map_to => $map_from) {
             PMA_array_write($map_to, $c, PMA_array_read($map_from, $c));
             PMA_array_remove($map_from, $c);
         }
@@ -504,19 +525,19 @@ class ConfigFile
     public function getConfigArray()
     {
         $this->_flattenArrayResult = array();
-        array_walk($_SESSION[$this->id], array($this, '_flattenArray'), '');
+        array_walk($_SESSION[$this->_id], array($this, '_flattenArray'), '');
         $c = $this->_flattenArrayResult;
         $this->_flattenArrayResult = null;
 
         $persistKeys = array_diff(
-            array_keys($this->persistKeys),
+            array_keys($this->_persistKeys),
             array_keys($c)
         );
         foreach ($persistKeys as $k) {
             $c[$k] = $this->getDefault($k);
         }
 
-        foreach ($this->cfgUpdateReadMapping as $map_to => $map_from) {
+        foreach ($this->_cfgUpdateReadMapping as $map_to => $map_from) {
             if (!isset($c[$map_from])) {
                 continue;
             }
diff --git a/libraries/config/Form.class.php b/libraries/config/Form.class.php
index f17c747e30..d82e66b69e 100644
--- a/libraries/config/Form.class.php
+++ b/libraries/config/Form.class.php
@@ -42,7 +42,7 @@ class Form
      * Caches field types, indexed by field names
      * @var array
      */
-    private $fieldsTypes;
+    private $_fieldsTypes;
 
     /**
      * Constructor, reads default config values
@@ -67,8 +67,8 @@ class Form
     public function getOptionType($option_name)
     {
         $key = ltrim(substr($option_name, strrpos($option_name, '/')), '/');
-        return isset($this->fieldsTypes[$key])
-            ? $this->fieldsTypes[$key]
+        return isset($this->_fieldsTypes[$key])
+            ? $this->_fieldsTypes[$key]
             : null;
     }
 
@@ -169,7 +169,7 @@ class Form
     }
 
     /**
-     * Reads fields' types to $this->fieldsTypes
+     * Reads fields' types to $this->_fieldsTypes
      *
      * @return void
      */
@@ -178,7 +178,7 @@ class Form
         $cf = ConfigFile::getInstance();
         foreach ($this->fields as $name => $path) {
             if (strpos($name, ':group:') === 0) {
-                $this->fieldsTypes[$name] = 'group';
+                $this->_fieldsTypes[$name] = 'group';
                 continue;
             }
             $v = $cf->getDbEntry($path);
@@ -187,7 +187,7 @@ class Form
             } else {
                 $type = gettype($cf->getDefault($path));
             }
-            $this->fieldsTypes[$name] = $type;
+            $this->_fieldsTypes[$name] = $type;
         }
     }
 
diff --git a/libraries/config/FormDisplay.class.php b/libraries/config/FormDisplay.class.php
index 6902dc235b..09bfd753f0 100644
--- a/libraries/config/FormDisplay.class.php
+++ b/libraries/config/FormDisplay.class.php
@@ -22,6 +22,8 @@ require_once './libraries/js_escape.lib.php';
 
 /**
  * Form management class, displays and processes forms
+ *
+ * @package PhpMyAdmin
  */
 class FormDisplay
 {
@@ -29,7 +31,7 @@ class FormDisplay
      * Form list
      * @var Form[]
      */
-    private $forms = array();
+    private $_forms = array();
 
     /**
      * Stores validation errors, indexed by paths
@@ -37,49 +39,52 @@ class FormDisplay
      * [path] is a string storing error associated with single field
      * @var array
      */
-    private $errors = array();
+    private $_errors = array();
 
     /**
      * Paths changed so that they can be used as HTML ids, indexed by paths
      * @var array
      */
-    private $translated_paths = array();
+    private $_translated_paths = array();
 
     /**
      * Server paths change indexes so we define maps from current server
      * path to the first one, indexed by work path
      * @var array
      */
-    private $system_paths = array();
+    private $_system_paths = array();
 
     /**
      * Language strings which will be sent to PMA_messages JS variable
      * Will be looked up in $GLOBALS: str{value} or strSetup{value}
      * @var array
      */
-    private $js_lang_strings = array();
+    private $_js_lang_strings = array();
 
     /**
      * Tells whether forms have been validated
      * @var bool
      */
-    private $is_validated = true;
+    private $_is_validated = true;
 
     /**
      * Dictionary with user preferences keys
      * @var array
      */
-    private $userprefs_keys;
+    private $_userprefs_keys;
 
     /**
      * Dictionary with disallowed user preferences keys
      * @var array
      */
-    private $userprefs_disallow;
+    private $_userprefs_disallow;
 
+    /**
+     * Constructor
+     */
     public function __construct()
     {
-        $this->js_lang_strings = array(
+        $this->_js_lang_strings = array(
             'error_nan_p' => __('Not a positive number'),
             'error_nan_nneg' => __('Not a non-negative number'),
             'error_incorrect_port' => __('Not a valid port number'),
@@ -95,17 +100,19 @@ class FormDisplay
      * @param string $form_name
      * @param array  $form
      * @param int    $server_id 0 if new server, validation; >= 1 if editing a server
+     *
+     * @return void
      */
     public function registerForm($form_name, array $form, $server_id = null)
     {
-        $this->forms[$form_name] = new Form($form_name, $form, $server_id);
-        $this->is_validated = false;
-        foreach ($this->forms[$form_name]->fields as $path) {
+        $this->_forms[$form_name] = new Form($form_name, $form, $server_id);
+        $this->_is_validated = false;
+        foreach ($this->_forms[$form_name]->fields as $path) {
             $work_path = $server_id === null
                 ? $path
                 : str_replace('Servers/1/', "Servers/$server_id/", $path);
-            $this->system_paths[$work_path] = $path;
-            $this->translated_paths[$work_path] = str_replace('/', '-', $work_path);
+            $this->_system_paths[$work_path] = $path;
+            $this->_translated_paths[$work_path] = str_replace('/', '-', $work_path);
         }
     }
 
@@ -125,8 +132,8 @@ class FormDisplay
         }
 
         // save forms
-        if (count($this->forms) > 0) {
-            return $this->save(array_keys($this->forms), $allow_partial_save);
+        if (count($this->_forms) > 0) {
+            return $this->save(array_keys($this->_forms), $allow_partial_save);
         }
         return false;
     }
@@ -138,19 +145,19 @@ class FormDisplay
      */
     private function _validate()
     {
-        if ($this->is_validated) {
+        if ($this->_is_validated) {
             return;
         }
 
         $cf = ConfigFile::getInstance();
         $paths = array();
         $values = array();
-        foreach ($this->forms as $form) {
+        foreach ($this->_forms as $form) {
             /* @var $form Form */
             $paths[] = $form->name;
             // collect values and paths
             foreach ($form->fields as $path) {
-                $work_path = array_search($path, $this->system_paths);
+                $work_path = array_search($path, $this->_system_paths);
                 $values[$path] = $cf->getValue($work_path);
                 $paths[] = $path;
             }
@@ -161,18 +168,18 @@ class FormDisplay
 
         // change error keys from canonical paths to work paths
         if (is_array($errors) && count($errors) > 0) {
-            $this->errors = array();
+            $this->_errors = array();
             foreach ($errors as $path => $error_list) {
-                $work_path = array_search($path, $this->system_paths);
+                $work_path = array_search($path, $this->_system_paths);
                 // field error
                 if (!$work_path) {
                     // form error, fix path
                     $work_path = $path;
                 }
-                $this->errors[$work_path] = $error_list;
+                $this->_errors[$work_path] = $error_list;
             }
         }
-        $this->is_validated = true;
+        $this->_is_validated = true;
     }
 
     /**
@@ -189,14 +196,14 @@ class FormDisplay
 
         $js = array();
         $js_default = array();
-        $tabbed_form = $tabbed_form && (count($this->forms) > 1);
+        $tabbed_form = $tabbed_form && (count($this->_forms) > 1);
         $validators = PMA_config_get_validators();
 
         display_form_top();
 
         if ($tabbed_form) {
             $tabs = array();
-            foreach ($this->forms as $form) {
+            foreach ($this->_forms as $form) {
                 $tabs[$form->name] = PMA_lang("Form_$form->name");
             }
             display_tabs_top($tabs);
@@ -204,7 +211,7 @@ class FormDisplay
 
         // valdiate only when we aren't displaying a "new server" form
         $is_new_server = false;
-        foreach ($this->forms as $form) {
+        foreach ($this->_forms as $form) {
             /* @var $form Form */
             if ($form->index === 0) {
                 $is_new_server = true;
@@ -219,13 +226,13 @@ class FormDisplay
         $this->_loadUserprefsInfo();
 
         // display forms
-        foreach ($this->forms as $form) {
+        foreach ($this->_forms as $form) {
             /* @var $form Form */
             $form_desc = isset($GLOBALS["strConfigForm_{$form->name}_desc"])
                 ? PMA_lang("Form_{$form->name}_desc")
                 : '';
-            $form_errors = isset($this->errors[$form->name])
-                ? $this->errors[$form->name] : null;
+            $form_errors = isset($this->_errors[$form->name])
+                ? $this->_errors[$form->name] : null;
             display_fieldset_top(
                 PMA_lang("Form_$form->name"),
                 $form_desc,
@@ -234,12 +241,12 @@ class FormDisplay
             );
 
             foreach ($form->fields as $field => $path) {
-                $work_path = array_search($path, $this->system_paths);
-                $translated_path = $this->translated_paths[$work_path];
+                $work_path = array_search($path, $this->_system_paths);
+                $translated_path = $this->_translated_paths[$work_path];
                 // always true/false for user preferences display
                 // otherwise null
-                $userprefs_allow = isset($this->userprefs_keys[$path])
-                    ? !isset($this->userprefs_disallow[$path])
+                $userprefs_allow = isset($this->_userprefs_keys[$path])
+                    ? !isset($this->_userprefs_disallow[$path])
                     : null;
                 // display input
                 $this->_displayFieldInput(
@@ -269,7 +276,7 @@ class FormDisplay
         if (!$js_lang_sent) {
             $js_lang_sent = true;
             $js_lang = array();
-            foreach ($this->js_lang_strings as $strName => $strValue) {
+            foreach ($this->_js_lang_strings as $strName => $strValue) {
                 $js_lang[] = "'$strName': '" . PMA_jsFormat($strValue, false) . '\'';
             }
             $js[] = "$.extend(PMA_messages, {\n\t" . implode(",\n\t", $js_lang) . '})';
@@ -324,8 +331,8 @@ class FormDisplay
             $opts['setvalue'] = $form->default[$system_path];
         }
 
-        if (isset($this->errors[$work_path])) {
-            $opts['errors'] = $this->errors[$work_path];
+        if (isset($this->_errors[$work_path])) {
+            $opts['errors'] = $this->_errors[$work_path];
         }
         switch ($form->getOptionType($field)) {
         case 'string':
@@ -411,13 +418,13 @@ class FormDisplay
     public function displayErrors()
     {
         $this->_validate();
-        if (count($this->errors) == 0) {
+        if (count($this->_errors) == 0) {
             return;
         }
 
-        foreach ($this->errors as $system_path => $error_list) {
-            if (isset($this->system_paths[$system_path])) {
-                $path = $this->system_paths[$system_path];
+        foreach ($this->_errors as $system_path => $error_list) {
+            if (isset($this->_system_paths[$system_path])) {
+                $path = $this->_system_paths[$system_path];
                 $name = PMA_lang_name($path);
             } else {
                 $name = $GLOBALS["strConfigForm_$system_path"];
@@ -434,16 +441,16 @@ class FormDisplay
     public function fixErrors()
     {
         $this->_validate();
-        if (count($this->errors) == 0) {
+        if (count($this->_errors) == 0) {
             return;
         }
 
         $cf = ConfigFile::getInstance();
-        foreach (array_keys($this->errors) as $work_path) {
-            if (!isset($this->system_paths[$work_path])) {
+        foreach (array_keys($this->_errors) as $work_path) {
+            if (!isset($this->_system_paths[$work_path])) {
                 continue;
             }
-            $canonical_path = $this->system_paths[$work_path];
+            $canonical_path = $this->_system_paths[$work_path];
             $cf->set($work_path, $cf->getDefault($canonical_path));
         }
     }
@@ -500,11 +507,11 @@ class FormDisplay
             $this->_loadUserprefsInfo();
         }
 
-        $this->errors = array();
+        $this->_errors = array();
         foreach ($forms as $form_name) {
             /* @var $form Form */
-            if (isset($this->forms[$form_name])) {
-                $form = $this->forms[$form_name];
+            if (isset($this->_forms[$form_name])) {
+                $form = $this->_forms[$form_name];
             } else {
                 continue;
             }
@@ -514,8 +521,8 @@ class FormDisplay
                 : false;
             // grab POST values
             foreach ($form->fields as $field => $system_path) {
-                $work_path = array_search($system_path, $this->system_paths);
-                $key = $this->translated_paths[$work_path];
+                $work_path = array_search($system_path, $this->_system_paths);
+                $key = $this->_translated_paths[$work_path];
                 $type = $form->getOptionType($field);
 
                 // skip groups
@@ -529,7 +536,7 @@ class FormDisplay
                     if ($type == 'boolean') {
                         $_POST[$key] = false;
                     } else {
-                        $this->errors[$form->name][] = sprintf(
+                        $this->_errors[$form->name][] = sprintf(
                             __('Missing data for %s'),
                             '<i>' . PMA_lang_name($system_path) . '</i>'
                         );
@@ -539,13 +546,15 @@ class FormDisplay
                 }
 
                 // user preferences allow/disallow
-                if ($is_setup_script && isset($this->userprefs_keys[$system_path])) {
-                    if (isset($this->userprefs_disallow[$system_path])
+                if ($is_setup_script
+                    && isset($this->_userprefs_keys[$system_path])
+                ) {
+                    if (isset($this->_userprefs_disallow[$system_path])
                         && isset($_POST[$key . '-userprefs-allow'])
                     ) {
-                        unset($this->userprefs_disallow[$system_path]);
+                        unset($this->_userprefs_disallow[$system_path]);
                     } else if (!isset($_POST[$key . '-userprefs-allow'])) {
-                        $this->userprefs_disallow[$system_path] = true;
+                        $this->_userprefs_disallow[$system_path] = true;
                     }
                 }
 
@@ -574,7 +583,7 @@ class FormDisplay
                         $form->getOptionValueList($system_path)
                     );
                     if (! $successfully_validated) {
-                        $this->errors[$work_path][] = __('Incorrect value');
+                        $this->_errors[$work_path][] = __('Incorrect value');
                         $result = false;
                         continue;
                     }
@@ -611,7 +620,7 @@ class FormDisplay
         }
 
         // save forms
-        if ($allow_partial_save || empty($this->errors)) {
+        if ($allow_partial_save || empty($this->_errors)) {
             foreach ($to_save as $work_path => $path) {
                 // TrustedProxies requires changes before saving
                 if ($path == 'TrustedProxies') {
@@ -637,7 +646,10 @@ class FormDisplay
                 $cf->set($work_path, $values[$path], $path);
             }
             if ($is_setup_script) {
-                $cf->set('UserprefsDisallow', array_keys($this->userprefs_disallow));
+                $cf->set(
+                    'UserprefsDisallow',
+                    array_keys($this->_userprefs_disallow)
+                );
             }
         }
 
@@ -654,7 +666,7 @@ class FormDisplay
      */
     public function hasErrors()
     {
-        return count($this->errors) > 0;
+        return count($this->_errors) > 0;
     }
 
 
@@ -722,13 +734,13 @@ class FormDisplay
      */
     private function _loadUserprefsInfo()
     {
-        if ($this->userprefs_keys === null) {
-            $this->userprefs_keys = array_flip(PMA_read_userprefs_fieldnames());
+        if ($this->_userprefs_keys === null) {
+            $this->_userprefs_keys = array_flip(PMA_read_userprefs_fieldnames());
             // read real config for user preferences display
             $userprefs_disallow = defined('PMA_SETUP')
                 ? ConfigFile::getInstance()->get('UserprefsDisallow', array())
                 : $GLOBALS['cfg']['UserprefsDisallow'];
-            $this->userprefs_disallow = array_flip($userprefs_disallow);
+            $this->_userprefs_disallow = array_flip($userprefs_disallow);
         }
     }