diff --git a/core/pagecontroller/Document.php b/core/pagecontroller/Document.php
index 3a5e6c4fc..97eb5131b 100644
--- a/core/pagecontroller/Document.php
+++ b/core/pagecontroller/Document.php
@@ -110,7 +110,7 @@ class Document extends APFObject implements DomNode {
    protected $parent = null;
 
    /**
-    * @var string[][] $attributes XML attributes of the current node.
+    * @var string[] $attributes XML attributes of the current node.
     */
    protected $attributes = [];
 
diff --git a/extensions/form/client/taglib/AddFormControlClientValidatorTag.php b/extensions/form/client/taglib/AddFormControlClientValidatorTag.php
index b418f0277..c4ed0952f 100644
--- a/extensions/form/client/taglib/AddFormControlClientValidatorTag.php
+++ b/extensions/form/client/taglib/AddFormControlClientValidatorTag.php
@@ -112,6 +112,7 @@ public function onAfterAppend() {
 
    public function reset() {
       // nothing to do as client listeners cannot be reset
+      return $this;
    }
 
 }
diff --git a/extensions/form/client/taglib/ClientValidationListenerTag.php b/extensions/form/client/taglib/ClientValidationListenerTag.php
index 91d61e1f1..47e3012d0 100644
--- a/extensions/form/client/taglib/ClientValidationListenerTag.php
+++ b/extensions/form/client/taglib/ClientValidationListenerTag.php
@@ -113,6 +113,7 @@ public function transform() {
 
    public function reset() {
       // nothing to do as client listeners cannot be reset
+      return $this;
    }
 
 }
diff --git a/extensions/form/client/taglib/FormClientErrorDisplayTag.php b/extensions/form/client/taglib/FormClientErrorDisplayTag.php
index 94f1800a7..4493eb4c6 100644
--- a/extensions/form/client/taglib/FormClientErrorDisplayTag.php
+++ b/extensions/form/client/taglib/FormClientErrorDisplayTag.php
@@ -84,6 +84,7 @@ public function transform() {
 
    public function reset() {
       // nothing to do as client errors cannot be reset
+      return $this;
    }
 
 }
diff --git a/extensions/form/client/taglib/GetClientFormValidationTag.php b/extensions/form/client/taglib/GetClientFormValidationTag.php
index fb0c8e18c..172118c38 100644
--- a/extensions/form/client/taglib/GetClientFormValidationTag.php
+++ b/extensions/form/client/taglib/GetClientFormValidationTag.php
@@ -219,6 +219,7 @@ public function onAfterAppend() {
 
    public function reset() {
       // nothing to do as client validation rule generation takes no user input
+      return $this;
    }
 
 }
diff --git a/tools/form/FormControl.php b/tools/form/FormControl.php
index 9f283c2eb..b06c35d78 100644
--- a/tools/form/FormControl.php
+++ b/tools/form/FormControl.php
@@ -366,7 +366,7 @@ public function isFilled();
     * @version
     * Version 0.1, 03.02.2010<br />
     */
-   public function appendCssClass($class);
+   public function appendCssClass(string $class);
 
    /**
     * Adds an additional attribute to the white list of the control.
@@ -380,7 +380,7 @@ public function appendCssClass($class);
     * @version
     * Version 0.1, 21.07.2010<br />
     */
-   public function addAttributeToWhiteList($name);
+   public function addAttributeToWhiteList(string $name);
 
    /**
     * Adds a set of additional attributes to the white list of the control.
diff --git a/tools/form/FormControlFinder.php b/tools/form/FormControlFinder.php
index 8c92452b2..722a387a8 100644
--- a/tools/form/FormControlFinder.php
+++ b/tools/form/FormControlFinder.php
@@ -44,7 +44,7 @@ interface FormControlFinder {
     * @version
     * Version 0.1, 21.01.2007<br />
     */
-   public function getFormElementByID($id);
+   public function getFormElementByID(string $id);
 
    /**
     * Returns a list of form controls with the given name.
@@ -57,7 +57,7 @@ public function getFormElementByID($id);
     * @version
     * Version 0.1, 16.08.2010<br />
     */
-   public function getFormElementsByName($name);
+   public function getFormElementsByName(string $name);
 
    /**
     * Returns a list of form elements addressed by their tag name.
@@ -72,7 +72,7 @@ public function getFormElementsByName($name);
     * Version 0.1, 14.06.2008 (API change: do use this function instead of getFormElementsByType()!)<br />
     * Version 0.2, 12.12.2012 (Refactoring due to tag renaming)<br />
     */
-   public function getFormElementsByTagName($tagName);
+   public function getFormElementsByTagName(string $tagName);
 
    /**
     * Returns a list of form elements addressed by their implementation class name.
@@ -100,7 +100,7 @@ public function getFormElementsByType(string $class): array;
     * @version
     * Version 0.1, 03.09.2008<br />
     */
-   public function getMarker($markerName);
+   public function getMarker(string $markerName);
 
    /**
     * Returns a reference on the form element identified by the given name.
@@ -115,7 +115,7 @@ public function getMarker($markerName);
     * Version 0.1, 07.01.2007<br />
     * Version 0.2, 12.09.2009 (Corrected debug message)<br />
     */
-   public function getFormElementByName($name);
+   public function getFormElementByName(string $name);
 
    /**
     * Let's you retrieve an &lt;form:getstring /&gt; tag instance with the specified name.
@@ -129,6 +129,6 @@ public function getFormElementByName($name);
     * @version
     * Version 0.1, 17.01.2012<br />
     */
-   public function getLabel($name);
+   public function getLabel(string $name);
 
 }
diff --git a/tools/form/FormElement.php b/tools/form/FormElement.php
index b9bc8d557..0d309af92 100644
--- a/tools/form/FormElement.php
+++ b/tools/form/FormElement.php
@@ -63,6 +63,8 @@ public function isValid();
     * <p/>
     * What happens when resetting a form control is up to the dedicated implementation.
     *
+    * @return $this This instance for further usage.
+    *
     * @author Christian Achatz
     * @version
     * Version 0.1, 06.09.2014 (ID#206: Added interface enhancement to allow resetting)<br />
diff --git a/tools/form/FormMarker.php b/tools/form/FormMarker.php
index 8083441ea..6a184180c 100644
--- a/tools/form/FormMarker.php
+++ b/tools/form/FormMarker.php
@@ -41,7 +41,7 @@ interface FormMarker {
     * @version
     * Version 0.1, 23.08.2014<br />
     */
-   public function addContentAfter($content);
+   public function addContentAfter(string $content);
 
    /**
     * Allows you to add content (e.g. HTML, text) BEFORE the form marker.
@@ -54,5 +54,5 @@ public function addContentAfter($content);
     * @version
     * Version 0.1, 23.08.2014<br />
     */
-   public function addContentBefore($content);
+   public function addContentBefore(string $content);
 }
diff --git a/tools/form/HtmlForm.php b/tools/form/HtmlForm.php
index 7cbdf4742..d47f768d8 100644
--- a/tools/form/HtmlForm.php
+++ b/tools/form/HtmlForm.php
@@ -110,6 +110,8 @@ public static function clearModelToFormControlMapper();
     *
     * @param string $action The action URL of the form.
     *
+    * @return $this This instance for further usage.
+    *
     * @author Christian Schäfer
     * @version
     * Version 0.1, 07.01.2007<br />
diff --git a/tools/form/mixin/FormControlFinder.php b/tools/form/mixin/FormControlFinder.php
index 1711f8189..c01eb5b84 100644
--- a/tools/form/mixin/FormControlFinder.php
+++ b/tools/form/mixin/FormControlFinder.php
@@ -46,7 +46,7 @@ trait FormControlFinder {
     * @return FormControl A reference on the form element.
     * @throws FormException In case the form element cannot be found.
     */
-   public function getFormElementByID($id) {
+   public function getFormElementByID(string $id) {
 
       if (count($this->children) > 0) {
          foreach ($this->children as &$child) {
@@ -89,7 +89,7 @@ public function getFormElementByID($id) {
     * @return DynamicFormElementMarkerTag|DomNode The marker.
     * @throws FormException In case the marker cannot be found.
     */
-   public function getMarker($markerName) {
+   public function getMarker(string $markerName) {
       return $this->getFormElementByName($markerName);
    }
 
@@ -99,7 +99,7 @@ public function getMarker($markerName) {
     * @return FormControl A reference on the form element.
     * @throws FormException In case the form element cannot be found.
     */
-   public function getFormElementByName($name) {
+   public function getFormElementByName(string $name) {
 
       if (count($this->children) > 0) {
          foreach ($this->children as &$child) {
@@ -142,7 +142,7 @@ public function getFormElementByName($name) {
     * @return LanguageLabelTag The instance of the desired label.
     * @throws FormException In case no label can be found.
     */
-   public function getLabel($name) {
+   public function getLabel(string $name) {
       if (count($this->children) > 0) {
          foreach ($this->children as &$child) {
 
@@ -183,7 +183,7 @@ public function getLabel($name) {
     *
     * @return FormControl[] The list of form controls with the given name.
     */
-   public function getFormElementsByName($name) {
+   public function getFormElementsByName(string $name) {
       $elements = [];
       if (count($this->children) > 0) {
          foreach ($this->children as &$child) {
@@ -209,7 +209,7 @@ public function getFormElementsByName($name) {
     * @return FormControl[] A list of references on the form elements.
     * @throws FormException In case the form element cannot be found or desired tag is not registered.
     */
-   public function getFormElementsByTagName($tagName) {
+   public function getFormElementsByTagName(string $tagName) {
 
       /* @var $form HtmlFormTag */
       if ($this instanceof HtmlForm) {
diff --git a/tools/form/multifileupload/biz/MultiFileUploadManager.php b/tools/form/multifileupload/biz/MultiFileUploadManager.php
index e37539c34..f508912a6 100644
--- a/tools/form/multifileupload/biz/MultiFileUploadManager.php
+++ b/tools/form/multifileupload/biz/MultiFileUploadManager.php
@@ -168,7 +168,7 @@ private function checkSessionFiles() {
     * @param array $file
     * @param boolean $js True, in case of java script upload, false otherwise.
     *
-    * @return boolean
+    * @return boolean|array
     * @throws FormException
     *
     * @author Werner Liemberger <wpublicmail@gmail.com>
@@ -311,7 +311,7 @@ private function getFileLink($uploadname) {
     * @param string $dir - Zielverzeichnis
     * @param string $name - Zieldateiname
     *
-    * @return File::moveTo
+    * @return bool
     *
     * @author Werner Liemberger <wpublicmail@gmail.com>
     * @version 1.0, 14.03.2011<br>
@@ -381,7 +381,7 @@ public function getFiles() {
     *
     * @param string $uploadname - Dateiname
     *
-    * @return array
+    * @return mixed
     *
     * @author Werner Liemberger <wpublicmail@gmail.com>
     * @version 1.0, 14.3.2011<br>
diff --git a/tools/form/multifileupload/pres/taglib/MultiFileUploadTag.php b/tools/form/multifileupload/pres/taglib/MultiFileUploadTag.php
index a986cf4a2..c47536ce1 100644
--- a/tools/form/multifileupload/pres/taglib/MultiFileUploadTag.php
+++ b/tools/form/multifileupload/pres/taglib/MultiFileUploadTag.php
@@ -174,8 +174,8 @@ public function transform() {
     */
    private function createUploadButton() {
       return '<div id="' . $this->uploadFieldName . '_file_upload_container"><input type="file" name="' . $this->uploadFieldName . '" id="' . $this->uploadFieldName . '" multiple="multiple" /><button>'
-      . $this->languageConfig->getValue('upload.button.label') . '</button><div class="uploadlabel">'
-      . $this->languageConfig->getValue('upload.label') . '</div></div>';
+            . $this->languageConfig->getValue('upload.button.label') . '</button><div class="uploadlabel">'
+            . $this->languageConfig->getValue('upload.label') . '</div></div>';
    }
 
    /**
@@ -188,8 +188,8 @@ private function createUploadButton() {
     */
    private function createDialogFileDelete() {
       return '<div class="confirm_delete ui-dialog-content ui-widget-content dialog_confirm_delete" title="'
-      . $this->languageConfig->getValue('delete.title') . '">'
-      . $this->languageConfig->getValue('delete.message') . '</div>';
+            . $this->languageConfig->getValue('delete.title') . '">'
+            . $this->languageConfig->getValue('delete.message') . '</div>';
    }
 
    /**
@@ -202,8 +202,8 @@ private function createDialogFileDelete() {
     */
    private function createDialogFileSize() {
       return '<div class="filesize_dialog ui-dialog-content ui-widget-content" title="'
-      . $this->languageConfig->getValue('filesize.title') . '">'
-      . $this->languageConfig->getValue('filesize.message') . ' ' . $this->manager->getMaxFileSizeWithUnit() . '</div>';
+            . $this->languageConfig->getValue('filesize.title') . '">'
+            . $this->languageConfig->getValue('filesize.message') . ' ' . $this->manager->getMaxFileSizeWithUnit() . '</div>';
    }
 
    /**
@@ -216,8 +216,8 @@ private function createDialogFileSize() {
     */
    private function createDialogFileType() {
       return '<div class="filetype_dialog ui-dialog-content ui-widget-content" title="'
-      . $this->languageConfig->getValue('filetype.title') . '">'
-      . $this->languageConfig->getValue('filetype.message') . ' ' . $this->createFileExtensionFromMimeType($this->manager->getMimeTypes()) . '</div>';
+            . $this->languageConfig->getValue('filetype.title') . '">'
+            . $this->languageConfig->getValue('filetype.message') . ' ' . $this->createFileExtensionFromMimeType($this->manager->getMimeTypes()) . '</div>';
    }
 
    /**
@@ -566,6 +566,8 @@ public function reset() {
          $this->manager->deleteFile($file);
          $this->manager->deleteFileFromSession($file);
       }
+
+      return $this;
    }
 
 }
diff --git a/tools/form/provider/csrf/CSRFHashProvider.php b/tools/form/provider/csrf/CSRFHashProvider.php
index 52dd6a2c1..4d434c7cb 100644
--- a/tools/form/provider/csrf/CSRFHashProvider.php
+++ b/tools/form/provider/csrf/CSRFHashProvider.php
@@ -41,6 +41,6 @@ interface CSRFHashProvider {
     * @version
     * Version 0.1, 06.11.2010
     */
-   public function generateHash($salt);
+   public function generateHash(string $salt);
 
 }
diff --git a/tools/form/provider/csrf/EncryptedSIDHashProvider.php b/tools/form/provider/csrf/EncryptedSIDHashProvider.php
index e00e5d4df..5aa3d43dd 100644
--- a/tools/form/provider/csrf/EncryptedSIDHashProvider.php
+++ b/tools/form/provider/csrf/EncryptedSIDHashProvider.php
@@ -42,7 +42,7 @@ class EncryptedSIDHashProvider extends APFObject implements CSRFHashProvider {
     * @version
     * Version 0.1, 29.10.2010
     */
-   public function generateHash($salt) {
+   public function generateHash(string $salt) {
       if (!defined('SID')) {
          session_start();
       }
diff --git a/tools/form/taglib/AbstractFormControl.php b/tools/form/taglib/AbstractFormControl.php
index c08f17b75..990b56803 100644
--- a/tools/form/taglib/AbstractFormControl.php
+++ b/tools/form/taglib/AbstractFormControl.php
@@ -312,6 +312,8 @@ public function isSent() {
    public function reset() {
       // reset value attribute as basic implementation as it applies in several cases
       $this->setAttribute('value', '');
+
+      return $this;
    }
 
    public function isChecked() {
@@ -391,7 +393,7 @@ public function addValidator(FormValidator $validator) {
       return $this;
    }
 
-   public function addAttributeToWhiteList($name) {
+   public function addAttributeToWhiteList(string $name) {
       $this->attributeWhiteList[] = $name;
 
       return $this;
@@ -403,7 +405,7 @@ public function addAttributesToWhiteList(array $names) {
       return $this;
    }
 
-   public function appendCssClass($class) {
+   public function appendCssClass(string $class) {
       $this->addAttribute('class', $class, ' ');
 
       return $this;
diff --git a/tools/form/taglib/ButtonTag.php b/tools/form/taglib/ButtonTag.php
index 2891b94d9..593db50fd 100644
--- a/tools/form/taglib/ButtonTag.php
+++ b/tools/form/taglib/ButtonTag.php
@@ -105,6 +105,7 @@ public function transform() {
 
    public function reset() {
       // nothing to do as buttons contain no user input.
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/CheckBoxTag.php b/tools/form/taglib/CheckBoxTag.php
index 08bb426c0..630704501 100644
--- a/tools/form/taglib/CheckBoxTag.php
+++ b/tools/form/taglib/CheckBoxTag.php
@@ -82,6 +82,8 @@ public function transform() {
 
    public function reset() {
       $this->uncheck();
+
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/DateSelectorTag.php b/tools/form/taglib/DateSelectorTag.php
index 7a633d60d..6b9559dd5 100644
--- a/tools/form/taglib/DateSelectorTag.php
+++ b/tools/form/taglib/DateSelectorTag.php
@@ -484,6 +484,8 @@ public function reset() {
       $this->getYearControl()->reset();
       $this->getMonthControl()->reset();
       $this->getDayControl()->reset();
+
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/DynamicFormElementMarkerTag.php b/tools/form/taglib/DynamicFormElementMarkerTag.php
index 6b1aeb337..283827e50 100644
--- a/tools/form/taglib/DynamicFormElementMarkerTag.php
+++ b/tools/form/taglib/DynamicFormElementMarkerTag.php
@@ -40,7 +40,7 @@ public function transform() {
       return '';
    }
 
-   public function addContentBefore($content) {
+   public function addContentBefore(string $content) {
       $objectId = $this->getObjectId();
       $this->getParent()->setContent(str_replace(
                   '<' . $objectId . ' />',
@@ -51,7 +51,7 @@ public function addContentBefore($content) {
       return $this;
    }
 
-   public function addContentAfter($content) {
+   public function addContentAfter(string $content) {
       $objectId = $this->getObjectId();
       $this->getParent()->setContent(str_replace(
                   '<' . $objectId . ' />',
@@ -64,6 +64,7 @@ public function addContentAfter($content) {
 
    public function reset() {
       // nothing to do as markers don't generate output
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/FileUploadTag.php b/tools/form/taglib/FileUploadTag.php
index f96cca333..9d12aa4fc 100644
--- a/tools/form/taglib/FileUploadTag.php
+++ b/tools/form/taglib/FileUploadTag.php
@@ -249,6 +249,8 @@ public function getFile() {
 
    public function reset() {
       unset($_FILES[$this->getAttribute('name')]);
+
+      return $this;
    }
 
    /**
diff --git a/tools/form/taglib/FormControlObserverBase.php b/tools/form/taglib/FormControlObserverBase.php
index 3e96f4b52..ce88297cf 100644
--- a/tools/form/taglib/FormControlObserverBase.php
+++ b/tools/form/taglib/FormControlObserverBase.php
@@ -66,6 +66,7 @@ public function transform() {
 
    public function reset() {
       // nothing to do as observer tags create no visible output
+      return $this;
    }
 
    /**
diff --git a/tools/form/taglib/FormErrorDisplayTag.php b/tools/form/taglib/FormErrorDisplayTag.php
index e8c04bebc..078af262b 100644
--- a/tools/form/taglib/FormErrorDisplayTag.php
+++ b/tools/form/taglib/FormErrorDisplayTag.php
@@ -74,6 +74,7 @@ public function transform() {
 
    public function reset() {
       // nothing to do as error display tags cannot be reset
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/FormGroupTag.php b/tools/form/taglib/FormGroupTag.php
index 5103e3652..b0357ec2f 100644
--- a/tools/form/taglib/FormGroupTag.php
+++ b/tools/form/taglib/FormGroupTag.php
@@ -93,6 +93,8 @@ public function reset() {
             $child->reset();
          }
       }
+
+      return $this;
    }
 
    public function show() {
diff --git a/tools/form/taglib/FormLabelTag.php b/tools/form/taglib/FormLabelTag.php
index 57cadb650..c6afed6d8 100644
--- a/tools/form/taglib/FormLabelTag.php
+++ b/tools/form/taglib/FormLabelTag.php
@@ -52,8 +52,8 @@ public function onParseTime() {
    public function transform() {
       if ($this->isVisible) {
          return '<label ' . $this->getSanitizedAttributesAsString($this->getAttributes()) . '>'
-         . $this->getContent()
-         . '</label>';
+               . $this->getContent()
+               . '</label>';
       }
 
       return '';
@@ -61,6 +61,7 @@ public function transform() {
 
    public function reset() {
       // nothing to do as labels cannot be reset
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/FormSuccessDisplayTag.php b/tools/form/taglib/FormSuccessDisplayTag.php
index feb15bbea..c3c7e597a 100644
--- a/tools/form/taglib/FormSuccessDisplayTag.php
+++ b/tools/form/taglib/FormSuccessDisplayTag.php
@@ -74,6 +74,7 @@ public function transform() {
 
    public function reset() {
       // nothing to do as success messages cannot be reset
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/HtmlFormTag.php b/tools/form/taglib/HtmlFormTag.php
index c7e4e4f62..a809ff5de 100644
--- a/tools/form/taglib/HtmlFormTag.php
+++ b/tools/form/taglib/HtmlFormTag.php
@@ -199,6 +199,8 @@ public function reset() {
             $child->reset();
          }
       }
+
+      return $this;
    }
 
    /**
@@ -323,12 +325,16 @@ public function getTagClass($tagName) {
     *
     * @param string $content The desired content
     *
+    * @return $this This instance for further usage.
+    *
     * @author Christian Achatz
     * @version
     * Version 0.1, 05.01.2007<br />
     */
    public function addFormContent($content) {
       $this->content .= $content;
+
+      return $this;
    }
 
    /**
@@ -337,6 +343,8 @@ public function addFormContent($content) {
     * @param string $markerName the desired marker name
     * @param string $content the content to add
     *
+    * @return $this This instance for further usage.
+    *
     * @author Christian Achatz
     * @version
     * Version 0.1, 03.09.2008<br />
@@ -344,6 +352,8 @@ public function addFormContent($content) {
     */
    public function addFormContentBeforeMarker($markerName, $content) {
       $this->getMarker($markerName)->addContentBefore($content);
+
+      return $this;
    }
 
    /**
@@ -352,6 +362,8 @@ public function addFormContentBeforeMarker($markerName, $content) {
     * @param string $markerName the desired marker name
     * @param string $content the content to add
     *
+    * @return $this This instance for further usage.
+    *
     * @author Christian Achatz
     * @version
     * Version 0.1, 05.09.2008<br />
@@ -359,6 +371,8 @@ public function addFormContentBeforeMarker($markerName, $content) {
     */
    public function addFormContentAfterMarker($markerName, $content) {
       $this->getMarker($markerName)->addContentAfter($content);
+
+      return $this;
    }
 
    /**
@@ -443,6 +457,8 @@ public function addFormElementAfterMarker($markerName, $elementType, array $elem
 
    public function setAction($action) {
       $this->setAttribute(self::ACTION_ATTRIBUTE_NAME, $action);
+
+      return $this;
    }
 
    /**
@@ -450,6 +466,8 @@ public function setAction($action) {
     *
     * @param string $name The attribute which should be added to the white list.
     *
+    * @return $this This instance for further usage.
+    *
     * @since 2.0
     *
     * @author Ralf Schubert, Christian Achatz
@@ -457,19 +475,25 @@ public function setAction($action) {
     * Version 0.1, 21.07.2010<br />
     * Version 0.2, 08.06.2013 (Re-introduced white-list modification for form tag)<br />
     */
-   public function addAttributeToWhitelist($name) {
+   public function addAttributeToWhitelist(string $name) {
       $this->attributeWhiteList[] = $name;
+
+      return $this;
    }
 
    /**
     * Defines, whether the form should be transformed at the definition place.
     *
+    * @return $this This instance for further usage.
+    *
     * @author Christian Achatz
     * @version
     * Version 0.1, 01.06.2008<br />
     */
    public function transformOnPlace() {
       $this->transformOnPlace = true;
+
+      return $this;
    }
 
    /**
diff --git a/tools/form/taglib/RadioButtonTag.php b/tools/form/taglib/RadioButtonTag.php
index ff8b6a658..74980a0d8 100644
--- a/tools/form/taglib/RadioButtonTag.php
+++ b/tools/form/taglib/RadioButtonTag.php
@@ -99,6 +99,8 @@ protected function presetValue() {
 
    public function reset() {
       $this->uncheck();
+
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/ResetButtonTag.php b/tools/form/taglib/ResetButtonTag.php
index 923a70bf8..53d9ec3c0 100644
--- a/tools/form/taglib/ResetButtonTag.php
+++ b/tools/form/taglib/ResetButtonTag.php
@@ -59,6 +59,7 @@ public function transform() {
 
    public function reset() {
       // nothing to do as buttons contain no user input
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/SelectBoxGroupTag.php b/tools/form/taglib/SelectBoxGroupTag.php
index ffad4f509..844c3c493 100644
--- a/tools/form/taglib/SelectBoxGroupTag.php
+++ b/tools/form/taglib/SelectBoxGroupTag.php
@@ -174,6 +174,8 @@ public function reset() {
       foreach ($this->children as &$child) {
          $child->deleteAttribute('selected');
       }
+
+      return $this;
    }
 
    /**
diff --git a/tools/form/taglib/SelectBoxOptionTag.php b/tools/form/taglib/SelectBoxOptionTag.php
index 5029330eb..58f54c4f3 100644
--- a/tools/form/taglib/SelectBoxOptionTag.php
+++ b/tools/form/taglib/SelectBoxOptionTag.php
@@ -59,11 +59,13 @@ public function onParseTime() {
     */
    public function transform() {
       return '<option ' . $this->getSanitizedAttributesAsString($this->attributes) . '>'
-      . $this->content . '</option>';
+            . $this->content . '</option>';
    }
 
    public function reset() {
       $this->deleteAttribute('selected');
+
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/SelectBoxTag.php b/tools/form/taglib/SelectBoxTag.php
index 2a9e64795..5cd0c91c8 100644
--- a/tools/form/taglib/SelectBoxTag.php
+++ b/tools/form/taglib/SelectBoxTag.php
@@ -505,6 +505,8 @@ public function reset() {
             $child->deleteAttribute('selected');
          }
       }
+
+      return $this;
    }
 
    /**
diff --git a/tools/form/taglib/TextAreaTag.php b/tools/form/taglib/TextAreaTag.php
index 513dd3c81..986045642 100644
--- a/tools/form/taglib/TextAreaTag.php
+++ b/tools/form/taglib/TextAreaTag.php
@@ -52,7 +52,7 @@ public function __construct() {
    public function transform() {
       if ($this->isVisible) {
          return '<textarea ' . $this->getSanitizedAttributesAsString($this->attributes) . '>'
-         . $this->content . '</textarea>';
+               . $this->content . '</textarea>';
       }
 
       return '';
@@ -113,6 +113,8 @@ public function isFilled() {
 
    public function reset() {
       $this->content = null;
+
+      return $this;
    }
 
    /**
diff --git a/tools/form/taglib/TimeSelectorTag.php b/tools/form/taglib/TimeSelectorTag.php
index 6f4c16b9d..11ebc3a27 100644
--- a/tools/form/taglib/TimeSelectorTag.php
+++ b/tools/form/taglib/TimeSelectorTag.php
@@ -436,6 +436,8 @@ public function reset() {
       if ($this->showSeconds !== false) {
          $this->getSecondsControl()->reset();
       }
+
+      return $this;
    }
 
 }
diff --git a/tools/form/taglib/ValidationListenerTag.php b/tools/form/taglib/ValidationListenerTag.php
index 918525cc7..c8633300d 100644
--- a/tools/form/taglib/ValidationListenerTag.php
+++ b/tools/form/taglib/ValidationListenerTag.php
@@ -95,6 +95,7 @@ public function transform() {
 
    public function reset() {
       // nothing to do as listener tags contain no user input
+      return $this;
    }
 
 }
diff --git a/tools/html/Iterator.php b/tools/html/Iterator.php
index 02f8d8ad9..ededd3764 100644
--- a/tools/html/Iterator.php
+++ b/tools/html/Iterator.php
@@ -41,6 +41,6 @@ interface Iterator {
     * @version
     * Version 0.1, 01.06.2008<br />
     */
-   public function fillDataContainer($data);
+   public function fillDataContainer(array $data = []);
 
 }
diff --git a/tools/html/taglib/HtmlIteratorTag.php b/tools/html/taglib/HtmlIteratorTag.php
index 64165d362..c2e00bd3b 100644
--- a/tools/html/taglib/HtmlIteratorTag.php
+++ b/tools/html/taglib/HtmlIteratorTag.php
@@ -132,7 +132,7 @@ public function transformOnPlace() {
       $this->transformOnPlace = true;
    }
 
-   public function fillDataContainer($data) {
+   public function fillDataContainer(array $data = []) {
       $this->dataContainer = $data;
 
       return $this;