diff --git a/classes/class.assStackQuestion.php b/classes/class.assStackQuestion.php
index 1b041c98..b096b488 100644
--- a/classes/class.assStackQuestion.php
+++ b/classes/class.assStackQuestion.php
@@ -889,7 +889,9 @@ public function loadFromDb(int $question_id): void
                     $prt_data = $prt_from_db_array[$name];
 
                     $total_value += $prt_data->value;
-                    $all_formative = false;
+                    if ($prt_data->value > 0) {
+                        $all_formative = false;
+                    }
                 } else {
                     $this->loadStandardPRT($name);
                 }
diff --git a/classes/class.assStackQuestionGUI.php b/classes/class.assStackQuestionGUI.php
index 51003fc7..ed4c3d42 100644
--- a/classes/class.assStackQuestionGUI.php
+++ b/classes/class.assStackQuestionGUI.php
@@ -337,12 +337,6 @@ public function getPreview($show_question_only = false, $showInlineFeedback = fa
 
         $question_preview = StackRenderIlias::renderQuestion($attempt_data, $display_options);
 
-		//Returns output (with page if needed)
-		if (!$show_question_only) {
-			// get page object output
-			$question_preview = $this->getILIASPage($question_preview);
-		}
-
         $question_preview .= StackRenderIlias::renderQuestionVariables(StackRandomisationIlias::getRandomisationData($this->object, $this->object->getSeed()));
 
         return assStackQuestionUtils::_getLatex($question_preview);
@@ -645,7 +639,9 @@ public function writeQuestionSpecificPostData()
 
             foreach ($prts_array as $name => $prt_data) {
                 $total_value += (float) $prt_data->value;
-                $all_formative = false;
+                if ((float) $prt_data->value > 0) {
+                    $all_formative = false;
+                }
             }
 
             if ($prts_array && !$all_formative && $total_value < 0.0000001) {
@@ -888,6 +884,62 @@ public function questionCheck(): bool
                     assStackQuestionDB::_deleteStackPrts($this->object->getId(), $prt_name);
 
                     $tpl->setOnScreenMessage('success', "prt deleted", true);
+                    return true;
+                }
+
+                if (isset($_POST['cmd']['save']['change_prt_name_' . $prt_name])) {
+                    $new_prt_name = $_POST['prt_' . $prt_name . '_name'];
+
+                    $new_prt_name = preg_replace('/[^A-Za-z0-9]/', '', $new_prt_name);
+
+                    if ($prt_name != $new_prt_name && !isset($this->object->prts[$new_prt_name])) {
+                        $new_prts = $this->object->prts;
+
+                        $prt = $new_prts[$prt_name];
+
+                        $new_prt_data = new stdClass();
+
+                        $new_prt_data->name = $new_prt_name;
+                        $new_prt_data->value = $prt->get_value();
+                        $new_prt_data->autosimplify = $prt->isSimplify();
+                        $new_prt_data->feedbackvariables = $prt->get_feedbackvariables_keyvals();
+                        $new_prt_data->firstnodename = $prt->get_first_node();
+                        $new_prt_data->nodes = $prt->get_nodes();
+
+                        $new_prts[$new_prt_name] = new stack_potentialresponse_tree_lite($new_prt_data, $prt->get_value());
+
+                        unset($new_prts[$prt_name]);
+
+                        $current_question_text = $this->object->getQuestion();
+                        $new_question_text = str_replace("[[feedback:" . $prt_name . "]]", "[[feedback:" . $new_prt_name . "]]", $current_question_text);
+                        $this->specific_post_data["question_text"] = $new_question_text;
+
+                        $current_specific_feedback = $this->object->specific_feedback;
+                        $new_specific_feedback = str_replace("[[feedback:" . $prt_name . "]]", "[[feedback:" . $new_prt_name . "]]", $current_specific_feedback);
+                        $this->specific_post_data["options_specific_feedback"] = $new_specific_feedback;
+
+                        $this->object->prts = $new_prts;
+
+                        assStackQuestionDB::_changePrtName($this->object->getId(), $prt_name, $new_prt_name);
+
+                        foreach ($this->specific_post_data as $key => $value) {
+                            if (strpos($key, 'prt_' . $prt_name) !== false) {
+                                $new_key = str_replace('prt_' . $prt_name, 'prt_' . $new_prt_name, $key);
+
+                                if (strpos($new_key, '_answernote') !== false) {
+                                    $this->specific_post_data[$new_key] = str_replace($prt_name, $new_prt_name, $value);
+                                } else {
+                                    $this->specific_post_data[$new_key] = $value;
+                                }
+
+                                unset($this->specific_post_data[$key]);
+                            }
+                        }
+
+                        $tpl->setOnScreenMessage('success', "prt name changed", true);
+                        return true;
+                    }
+
                     return true;
                 }
 
diff --git a/classes/import/MoodleXML/class.assStackQuestionMoodleImport.php b/classes/import/MoodleXML/class.assStackQuestionMoodleImport.php
index 06a2ad96..08db3d41 100644
--- a/classes/import/MoodleXML/class.assStackQuestionMoodleImport.php
+++ b/classes/import/MoodleXML/class.assStackQuestionMoodleImport.php
@@ -326,8 +326,9 @@ public function loadFromMoodleXML(SimpleXMLElement $question): bool
         $allformative = true;
 
         foreach ($question->prt as $prt_data) {
-            if ($prt_data->feedbackstyle > 0) {
-                $totalvalue += $prt_data->value;
+            $totalvalue += $prt_data->value;
+
+            if ($prt_data->value > 0) {
                 $allformative = false;
             }
         }
@@ -388,11 +389,11 @@ public function loadFromMoodleXML(SimpleXMLElement $question): bool
             $prt_data = $temp_prt_data;
 
             $prtvalue = 0;
+
             if (!$allformative) {
                 $prtvalue = $prt_data->value / $totalvalue;
             }
 
-
             $this->getQuestion()->prts[(string) $prt_data->name] = new stack_potentialresponse_tree_lite($prt_data, $prtvalue);
         }
 
diff --git a/classes/import/qti12/class.assStackQuestionImport.php b/classes/import/qti12/class.assStackQuestionImport.php
index b4cd98bc..ce16fc35 100644
--- a/classes/import/qti12/class.assStackQuestionImport.php
+++ b/classes/import/qti12/class.assStackQuestionImport.php
@@ -229,14 +229,14 @@ public function fromXML(&$item, $questionpool_id, &$tst_id, &$tst_object, &$ques
                         $node->truepenalty = $xml_node->getTruePenalty();
                         $node->trueanswernote = $xml_node->getTrueAnswerNote();
                         $node->truefeedback = $xml_node->getTrueFeedback();
-                        $node->truefeedbackformat = $xml_node->getTrueFeedbackFormat();
+                        $node->truefeedbackformat = 0;
 
                         $node->falsescore = $xml_node->getFalseScore();
                         $node->falsescoremode = $xml_node->getFalseScoreMode();
                         $node->falsepenalty = $xml_node->getFalsePenalty();
                         $node->falseanswernote = $xml_node->getFalseAnswerNote();
                         $node->falsefeedback = $xml_node->getFalseFeedback();
-                        $node->falsefeedbackformat = $xml_node->getFalseFeedbackFormat();
+                        $node->falsefeedbackformat = 0;
 
                         $prt_data->nodes[$node->nodename] = $node;
                     } catch (stack_exception $e) {
@@ -252,7 +252,9 @@ public function fromXML(&$item, $questionpool_id, &$tst_id, &$tst_object, &$ques
 
             foreach ($prts_array as $name => $prt_data) {
                 $total_value += (float) $prt_data->value;
-                $all_formative = false;
+                if ((float) $prt_data->value > 0) {
+                    $all_formative = false;
+                }
             }
 
             foreach ($prts_array as $name => $prt_data) {
diff --git a/classes/legacy/ui/question_authoring/class.assStackQuestionAuthoringGUI.php b/classes/legacy/ui/question_authoring/class.assStackQuestionAuthoringGUI.php
index 31b9e8f3..3be8a59d 100644
--- a/classes/legacy/ui/question_authoring/class.assStackQuestionAuthoringGUI.php
+++ b/classes/legacy/ui/question_authoring/class.assStackQuestionAuthoringGUI.php
@@ -452,6 +452,7 @@ public function getInputPart(stack_input $input)
 		$input_type->setOptions(array("algebraic" => $this->getPlugin()->txt('input_type_algebraic'),
 			"boolean" => $this->getPlugin()->txt('input_type_boolean'),
 			"matrix" => $this->getPlugin()->txt('input_type_matrix'),
+            "varmatrix" => $this->getPlugin()->txt('input_type_varmatrix'),
 			"singlechar" => $this->getPlugin()->txt('input_type_singlechar'),
 			"textarea" => $this->getPlugin()->txt('input_type_textarea'),
 			"checkbox" => $this->getPlugin()->txt('input_type_checkbox'),
@@ -602,21 +603,29 @@ public function getPRTPart(stack_potentialresponse_tree_lite $prt)
 
 		//Add general settings
 		//Creation of properties of this part
-		if ($prt_name == 'new_prt') {
-			$prt_name_input = new ilTextInputGUI($this->getPlugin()->txt('prt_name'), 'prt_' . $prt_name . '_name');
-		} else {
-			$prt_name_input = new ilNonEditableValueGUI($this->getPlugin()->txt('prt_name'), 'prt_' . $prt_name . '_name');
-		}
-		$prt_name_input->setInfo($this->getPlugin()->txt('prt_name_info'));
-		$prt_name_input->setRequired(TRUE);
 
-		//If new question, name first prt directly as prt1
-		if ($this->new_question == TRUE) {
-			$prt_name_input->setValue("prt1");
-		} else {
-			$prt_name_input->setValue($prt_name);
-		}
-		$settings_column->addFormProperty($prt_name_input);
+        $prt_name_input = new ilTextInputGUI($this->getPlugin()->txt('prt_name'), 'prt_' . $prt_name . '_name');
+        $prt_name_input->setInfo($this->getPlugin()->txt('prt_name_info'));
+        $prt_name_input->setRequired(TRUE);
+        $prt_name_input->setMaxLength(20);
+
+        if ($this->new_question == TRUE) {
+            $prt_name_input->setValue("prt1");
+        } else {
+            $prt_name_input->setValue($prt_name);
+        }
+
+        $settings_column->addFormProperty($prt_name_input);
+
+        if ($prt_name != 'new_prt') {
+            $change_prt_name = new ilButtonFormProperty($this->getPlugin()->txt('change_prt_name'), 'change_prt_name_' . $prt_name);
+            $change_prt_name->setAction('change_prt_name_' . $prt_name);
+            $change_prt_name->setCommand('save');
+
+            $settings_column->addFormProperty($change_prt_name);
+        } else {
+            $settings_column->addFormProperty($prt_name_input);
+        }
 
         $delete_prt = new ilButtonFormProperty($this->getPlugin()->txt('delete_prt'), 'delete_full_prt_' . $prt_name);
         $delete_prt->setAction('delete_full_prt_' . $prt_name);
diff --git a/classes/stack/cas/castext2/blocks/geogebra.block.php b/classes/stack/cas/castext2/blocks/geogebra.block.php
index 6af6547d..14e14195 100644
--- a/classes/stack/cas/castext2/blocks/geogebra.block.php
+++ b/classes/stack/cas/castext2/blocks/geogebra.block.php
@@ -333,9 +333,9 @@ public function compile($format, $options): ?MP_Node {
         $r->items[] = new MP_String('<div style="' . $style .
             '"><div class="geogebrabox" id="geogebrabox" style="width:100%;height:100%;"></div></div><script type="module">');
         // For binding we need to import the binding libraries.
-        $r->items[] = new MP_String("\nimport {stack_js} from '" . stack_cors_link('stackjsiframe.min.js') . "';\n");
+        $r->items[] = new MP_String("\nimport stack_js from '" . castext2_parser_utils::stack_cors_link('stackjsiframe.min.js') . "';\n");
         // TODO: minify.
-        $r->items[] = new MP_String("import {stack_geogebra} from '" . stack_cors_link('stackgeogebra.js') . "';\n");
+        $r->items[] = new MP_String("import stack_geogebra from '" . castext2_parser_utils::stack_cors_link('stackgeogebra.js') . "';\n");
 
         // Lets define the common bits of code.
         $commonprecode = 'var presetparams = {"id":"applet","appName":"classic","width":800,"height": 600,' .
diff --git a/classes/utils/class.assStackQuestionDB.php b/classes/utils/class.assStackQuestionDB.php
index 7f110e39..79404726 100644
--- a/classes/utils/class.assStackQuestionDB.php
+++ b/classes/utils/class.assStackQuestionDB.php
@@ -669,7 +669,7 @@ private static function _saveStackPRTs(assStackQuestion $question, string $purpo
 					"id" => array("integer", $db->nextId('xqcas_prts')),
 					"question_id" => array("integer", $question_id),
 					"name" => array("text", $question->prts[$prt_name]->get_name()),
-					"value" => array("text", $question->prts[$prt_name]->get_value() == null ? "1.0" : $question->prts[$prt_name]->get_value()),
+					"value" => array("text", $question->prts[$prt_name]->get_value() === null ? "1.0" : $question->prts[$prt_name]->get_value()),
 					"auto_simplify" => array("integer", $question->prts[$prt_name]->isSimplify() == null ? 0 : $question->prts[$prt_name]->isSimplify()),
 					"feedback_variables" => array("clob", $question->prts[$prt_name]->get_feedbackvariables_keyvals() == null ? "" : $question->prts[$prt_name]->get_feedbackvariables_keyvals()),
 					"first_node_name" => array("text", $question->prts[$prt_name]->get_first_node() == null ? '-1' : $question->prts[$prt_name]->get_first_node()),
@@ -689,7 +689,7 @@ private static function _saveStackPRTs(assStackQuestion $question, string $purpo
 					array(
 						"question_id" => array("integer", $question_id),
 						"name" => array("text", $question->prts[$prt_name]->get_name()),
-						"value" => array("text", $question->prts[$prt_name]->get_value() == null ? "1.0" : $question->prts[$prt_name]->get_value()),
+						"value" => array("text", $question->prts[$prt_name]->get_value() === null ? "1.0" : $question->prts[$prt_name]->get_value()),
 						"auto_simplify" => array("integer", $question->prts[$prt_name]->isSimplify() == null ? 0 : $question->prts[$prt_name]->isSimplify()),
 						"feedback_variables" => array("clob", $question->prts[$prt_name]->get_feedbackvariables_keyvals() == null ? "" : $question->prts[$prt_name]->get_feedbackvariables_keyvals()),
 						"first_node_name" => array("text", $question->prts[$prt_name]->get_first_node() == null ? '-1' : $question->prts[$prt_name]->get_first_node()),
@@ -1198,6 +1198,30 @@ public static function _deleteStackPrts(int $question_id, string $prt_name = '')
 		}
 	}
 
+    /**
+     * @param int $question_id
+     * @param string $old_prt_name
+     * @param string $new_prt_name
+     * @return bool
+     */
+    public static function _changePrtName(int $question_id, string $old_prt_name, string $new_prt_name): bool
+    {
+        global $DIC;
+        $db = $DIC->database();
+        $query = /** @lang text */
+            'UPDATE xqcas_prts SET name = ' . $db->quote($new_prt_name, 'text') . ' WHERE question_id = ' . $db->quote($question_id, 'integer') . ' AND name = ' . $db->quote($old_prt_name, 'text');
+
+        $query_nodes = /** @lang text */
+            'UPDATE xqcas_prt_nodes SET prt_name = ' . $db->quote($new_prt_name, 'text') . ' WHERE question_id = ' . $db->quote($question_id, 'integer') . ' AND prt_name = ' . $db->quote($old_prt_name, 'text');
+
+
+        if ($db->manipulate($query) && $db->manipulate($query_nodes)) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
 	/**
 	 * @param int $question_id
 	 * @param string $prt_name
diff --git a/classes/utils/class.assStackQuestionInitialization.php b/classes/utils/class.assStackQuestionInitialization.php
index 03416987..f1c12673 100644
--- a/classes/utils/class.assStackQuestionInitialization.php
+++ b/classes/utils/class.assStackQuestionInitialization.php
@@ -227,6 +227,8 @@ function get_config($section = 'qtype_stack')
         $configs->stackmaximaversion = "2023121100";
         $configs->version = "2023121100";
 
+        $configs->geogebrabaseurl = $saved_config['geogebra_base_url'] ?? '';
+
         return $configs;
     }
 }
diff --git a/classes/utils/class.assStackQuestionUtils.php b/classes/utils/class.assStackQuestionUtils.php
index 79b7b030..20e1d8d9 100644
--- a/classes/utils/class.assStackQuestionUtils.php
+++ b/classes/utils/class.assStackQuestionUtils.php
@@ -1165,7 +1165,9 @@ public static function _arrayToQuestion(array $array, assStackQuestion $question
 
         foreach ($prt_from_array as $name => $prt_data) {
             $total_value += $prt_data->value;
-            $all_formative = false;
+            if ($prt_data->value > 0) {
+                $all_formative = false;
+            }
         }
 
         if ($prt_from_array && !$all_formative && $total_value < 0.0000001) {
diff --git a/lang/ilias_de.lang b/lang/ilias_de.lang
index 76ab1801..17814fce 100644
--- a/lang/ilias_de.lang
+++ b/lang/ilias_de.lang
@@ -314,6 +314,7 @@ input_type_info#:#Typ des Eingabeelements, z.B. Formularfeld, Wahr/Falsch, mehrz
 input_type_algebraic#:#Algebraische Eingabe
 input_type_boolean#:#Wahr/Falsch
 input_type_matrix#:#Matrix
+input_type_varmatrix#:#Variable Matrix
 input_type_singlechar#:#Einzelzeichen
 input_type_textarea#:#Mehrzeilig
 input_box_size#:#Eingabebreite
@@ -520,6 +521,7 @@ add_new_prt#:#Neuer Rückmeldebaum (PRT)
 add_new_node#:#Neuer Knoten
 delete_node#:#Lösche Knoten
 delete_prt#:#Lösche Rückmeldebaum
+change_prt_name#:#Ändere Rückmeldebaum-Namen
 authoring_points_info#:#Die Gesamtpunktzahl der Frage können Sie unter "Bewertung" festlegen.
 authoring_input_creation_info#:#Um ein neues Eingabefeld anzulegen, geben Sie im Fragetext die Platzhalter "[[input:Eingabename]]" und "[[validation:Eingabename]]" ein. Um es zu löschen, löschen Sie die Platzhalter im Fragentext.
 input_hint#:#Hinweis
diff --git a/lang/ilias_en.lang b/lang/ilias_en.lang
index c6ff7072..3c93e38b 100644
--- a/lang/ilias_en.lang
+++ b/lang/ilias_en.lang
@@ -305,6 +305,7 @@ input_type_info#:#This determines the type of the input element, e.g. form field
 input_type_algebraic#:#Algebraic input
 input_type_boolean#:#True/False
 input_type_matrix#:#Matrix
+input_type_varmatrix#:#Variable matrix
 input_type_singlechar#:#Single character
 input_type_textarea#:#Text area
 input_box_size#:#Input box size
@@ -511,6 +512,7 @@ add_new_prt#:#New Potential response Tree
 add_new_node#:#New Node
 delete_node#:#Delete node
 delete_prt#:#Delete Potential response Tree
+change_prt_name#:#Change Potential response Tree name
 authoring_points_info#:#To set the total points of the question, go to label Scoring.
 authoring_input_creation_info#:#To create new inputs just type on the question text the placeholder: "[[input:your_input_name]]" and "[[validation:your_input_name]]", to delete an input just delete the input placeholder from question text.
 input_hint#:#Hint
diff --git a/plugin.php b/plugin.php
index ab04bf39..2d798b2f 100644
--- a/plugin.php
+++ b/plugin.php
@@ -20,7 +20,7 @@
 
 $id = "xqcas";
  
-$version = "8.6.10";
+$version = "8.7.0";
 
 $ilias_min_version = "8.00";
 $ilias_max_version = "8.999";