diff --git a/GUI/coregui/Models/ComboProperty.h b/GUI/coregui/Models/ComboProperty.h
index d2d4c91bad7b58cf622c82ddda10e908bd3772d9..c8cb09c48c9f3b56481d6be74a6ed5ab7ce340ad 100644
--- a/GUI/coregui/Models/ComboProperty.h
+++ b/GUI/coregui/Models/ComboProperty.h
@@ -29,7 +29,7 @@ public:
     ComboProperty();
 
     static ComboProperty fromList(const QStringList& values,
-                                  const QString& current_value = QString());
+                                  const QString& current_value = "");
 
     QString getValue() const;
     void setValue(const QString& name);
diff --git a/GUI/coregui/Models/GUIDomainSampleVisitor.h b/GUI/coregui/Models/GUIDomainSampleVisitor.h
index ffc6c4d75d0ad6334768adf7349a4a7effc777ee..21a2abe30dcf727ebf88d7b9bc3da77f3d717be4 100644
--- a/GUI/coregui/Models/GUIDomainSampleVisitor.h
+++ b/GUI/coregui/Models/GUIDomainSampleVisitor.h
@@ -37,7 +37,7 @@ public:
 
     SessionItem* populateSampleModel(SampleModel* sampleModel, MaterialModel* materialModel,
                                      const MultiLayer& sample,
-                                     const QString& sample_name = QString());
+                                     const QString& sample_name = "");
 
     using INodeVisitor::visit;
 
diff --git a/GUI/coregui/Models/GUIObjectBuilder.h b/GUI/coregui/Models/GUIObjectBuilder.h
index b10443ba9b7a4f4cfb1e10281835ac87dc70a630..ca05fe346a6aa4d04a0c867e54818a1c005e6dde 100644
--- a/GUI/coregui/Models/GUIObjectBuilder.h
+++ b/GUI/coregui/Models/GUIObjectBuilder.h
@@ -39,11 +39,11 @@ BA_CORE_API_ SessionItem* populateSampleModelFromSim(SampleModel* sampleModel,
 BA_CORE_API_ SessionItem* populateSampleModel(SampleModel* sampleModel,
                                               MaterialModel* materialModel,
                                               const MultiLayer& sample,
-                                              const QString& sample_name = QString());
+                                              const QString& sample_name = "");
 
 BA_CORE_API_ SessionItem* populateInstrumentModel(InstrumentModel* p_instrument_model,
                                                   const Simulation& simulation,
-                                                  const QString& instrument_name = QString());
+                                                  const QString& instrument_name = "");
 
 BA_CORE_API_ SessionItem* populateDocumentModel(DocumentModel* p_documentModel,
                                                 const Simulation& simulation);
diff --git a/GUI/coregui/Models/GroupInfo.cpp b/GUI/coregui/Models/GroupInfo.cpp
index 340a682141dbb5ea4060c47d7864b26eeacfd3cb..3ba3cb546bfbe9cea2c1a5d4917661ddd3e75494 100644
--- a/GUI/coregui/Models/GroupInfo.cpp
+++ b/GUI/coregui/Models/GroupInfo.cpp
@@ -39,7 +39,7 @@ void GroupInfo::add(const QString& itemType, const QString& itemLabel)
 
 QString GroupInfo::defaultType() const
 {
-    if (m_defaultItemType == QString() && m_info.size() != 0)
+    if (m_defaultItemType == "" && m_info.size() != 0)
         return m_info[0].m_itemType;
     return m_defaultItemType;
 }
diff --git a/GUI/coregui/Models/GroupInfo.h b/GUI/coregui/Models/GroupInfo.h
index 243be74877e52cf7014678f80ce6abf9970bc5ff..7d8d082c995a4d59152a5d7eebe6244fe70fad85 100644
--- a/GUI/coregui/Models/GroupInfo.h
+++ b/GUI/coregui/Models/GroupInfo.h
@@ -26,7 +26,7 @@
 class BA_CORE_API_ GroupInfo
 {
 public:
-    explicit GroupInfo(const QString& groupType = QString(), bool is_sorted = true);
+    explicit GroupInfo(const QString& groupType = "", bool is_sorted = true);
 
     void add(const QString& itemType, const QString& itemLabel);
 
diff --git a/GUI/coregui/Models/JobItemUtils.cpp b/GUI/coregui/Models/JobItemUtils.cpp
index 8bea5605ed3173dccf262078da5d952a15037b3d..cc51abf32349dbe4a143841f5d890c79493b1d4e 100644
--- a/GUI/coregui/Models/JobItemUtils.cpp
+++ b/GUI/coregui/Models/JobItemUtils.cpp
@@ -132,7 +132,7 @@ ComboProperty JobItemUtils::availableUnits(const IUnitConverter& converter)
     ComboProperty result;
     for (auto units : converter.availableUnits()) {
         auto unit_name = nameFromAxesUnits(units);
-        if (unit_name != QString())
+        if (unit_name != "")
             result << unit_name;
     }
 
diff --git a/GUI/coregui/Models/ModelPath.cpp b/GUI/coregui/Models/ModelPath.cpp
index 3790910735f015468b8bf70d988b7e83c00e4b41..cf1249aff2a90f2110fae3dfb12b7cb2bb479bf6 100644
--- a/GUI/coregui/Models/ModelPath.cpp
+++ b/GUI/coregui/Models/ModelPath.cpp
@@ -28,7 +28,7 @@ QString ModelPath::getPathFromIndex(const QModelIndex& index)
         std::reverse(namePath.begin(), namePath.end());
         return namePath.join("/");
     }
-    return QString();
+    return "";
 }
 
 // TODO cover with unit tests and simplify
diff --git a/GUI/coregui/Models/ModelUtils.h b/GUI/coregui/Models/ModelUtils.h
index bc2d0a0c28d834eb85c89bc7e9a496dedb66d837..cfe18ccc595ba814775d0b8e9c582a3f290a922b 100644
--- a/GUI/coregui/Models/ModelUtils.h
+++ b/GUI/coregui/Models/ModelUtils.h
@@ -26,7 +26,7 @@ class SessionModel;
 namespace ModelUtils
 {
 //! Returns list of top iten manes.
-BA_CORE_API_ QStringList topItemNames(SessionModel* model, const QString& modelType = QString());
+BA_CORE_API_ QStringList topItemNames(SessionModel* model, const QString& modelType = "");
 
 //! Iterates through all model indices and calls user function.
 BA_CORE_API_ void iterate(const QModelIndex& index, const QAbstractItemModel* model,
diff --git a/GUI/coregui/Models/SessionGraphicsItem.h b/GUI/coregui/Models/SessionGraphicsItem.h
index 85e9de65f2716a9e68180f932a3dec92bf19790f..1479c70b87b3bb5c63768ff4060654bd9d6ad8e6 100644
--- a/GUI/coregui/Models/SessionGraphicsItem.h
+++ b/GUI/coregui/Models/SessionGraphicsItem.h
@@ -25,7 +25,7 @@ public:
     static const QString P_YPOS;
 
 protected:
-    explicit SessionGraphicsItem(const QString& model_type = QString());
+    explicit SessionGraphicsItem(const QString& model_type = "");
 };
 
 #endif // BORNAGAIN_GUI_COREGUI_MODELS_SESSIONGRAPHICSITEM_H
diff --git a/GUI/coregui/Models/SessionItem.h b/GUI/coregui/Models/SessionItem.h
index 2c15604ec3872852bc24283d6976588efb1aabca..5356a38eaf476324c41a0907b4efcb607dd5b5f1 100644
--- a/GUI/coregui/Models/SessionItem.h
+++ b/GUI/coregui/Models/SessionItem.h
@@ -33,7 +33,7 @@ class BA_CORE_API_ SessionItem
 public:
     static const QString P_NAME;
 
-    explicit SessionItem(const QString& modelType = QString());
+    explicit SessionItem(const QString& modelType = "");
     virtual ~SessionItem();
     SessionModel* model() const;
     SessionItem* parent() const;
@@ -59,10 +59,10 @@ public:
     QVector<QString> acceptableDefaultItemTypes() const;
 
     // access tagged items
-    SessionItem* getItem(const QString& tag = QString(), int row = 0) const;
+    SessionItem* getItem(const QString& tag = "", int row = 0) const;
     template <typename T> T& item(const QString& tag) const;
-    QVector<SessionItem*> getItems(const QString& tag = QString()) const;
-    bool insertItem(int row, SessionItem* item, const QString& tag = QString());
+    QVector<SessionItem*> getItems(const QString& tag = "") const;
+    bool insertItem(int row, SessionItem* item, const QString& tag = "");
     SessionItem* takeItem(int row, const QString& tag);
 
     // convenience functions for properties
diff --git a/GUI/coregui/Models/SessionItemTags.cpp b/GUI/coregui/Models/SessionItemTags.cpp
index c7fd31285484ca0e250f5b213f2f9b29cc234f75..196ceaff52f193711b0c30223f310914c5e07897 100644
--- a/GUI/coregui/Models/SessionItemTags.cpp
+++ b/GUI/coregui/Models/SessionItemTags.cpp
@@ -114,7 +114,7 @@ int SessionItemTags::insertIndexFromTagRow(const QString& tagName, int row)
 QString SessionItemTags::tagFromIndex(int index) const
 {
     if (index < 0)
-        return QString();
+        return "";
 
     for (const auto& tag : m_tags) {
         if (index < tag.childCount)
@@ -123,7 +123,7 @@ QString SessionItemTags::tagFromIndex(int index) const
             index -= tag.childCount;
     }
 
-    return QString();
+    return "";
 }
 
 int SessionItemTags::childCount(const QString& tagName)
diff --git a/GUI/coregui/Models/SessionItemTags.h b/GUI/coregui/Models/SessionItemTags.h
index ca24a8d556fbff645c4fd80ff34781f0926bdbd5..0b4c7133ad3137a46dc29b61184cda3c9973c191 100644
--- a/GUI/coregui/Models/SessionItemTags.h
+++ b/GUI/coregui/Models/SessionItemTags.h
@@ -27,7 +27,7 @@ class BA_CORE_API_ SessionItemTags
 public:
     bool registerTag(const QString& name, int min, int max, const QStringList& modelTypes);
 
-    bool isValid(const QString& tagName, const QString& modelType = QString()) const;
+    bool isValid(const QString& tagName, const QString& modelType = "") const;
 
     QStringList modelTypesForTag(const QString& tagName) const;
 
diff --git a/GUI/coregui/Models/SessionModel.h b/GUI/coregui/Models/SessionModel.h
index 258ef6ed6357c5ac475f817a4cbf1291ab20dfd6..943d0d3cb15b49425750886b5e4e5498c38edd8a 100644
--- a/GUI/coregui/Models/SessionModel.h
+++ b/GUI/coregui/Models/SessionModel.h
@@ -55,7 +55,7 @@ public:
 
     QModelIndex indexOfItem(SessionItem* item) const;
     SessionItem* insertNewItem(QString model_type, const QModelIndex& parent = QModelIndex(),
-                               int row = -1, QString tag = QString());
+                               int row = -1, QString tag = "");
 
     QString getModelTag() const;
     QString getModelName() const;
@@ -63,8 +63,8 @@ public:
     QVector<QString> acceptableDefaultItemTypes(const QModelIndex& parent) const;
 
     virtual void clear();
-    void load(const QString& filename = QString());
-    void save(const QString& filename = QString());
+    void load(const QString& filename = "");
+    void save(const QString& filename = "");
 
     // Sets mimedata pointer of item being dragged
     void setDraggedItemType(const QString& type);
@@ -76,10 +76,10 @@ public:
     void writeTo(QXmlStreamWriter* writer, SessionItem* parent = 0);
 
     SessionItem* moveItem(SessionItem* item, SessionItem* new_parent = 0, int row = -1,
-                          const QString& tag = QString());
+                          const QString& tag = "");
 
     SessionItem* copyItem(const SessionItem* item_to_copy, SessionItem* new_parent = 0,
-                          const QString& tag = QString());
+                          const QString& tag = "");
 
     virtual SessionModel* createCopy(SessionItem* parent = 0);
 
diff --git a/GUI/coregui/Models/SessionXML.h b/GUI/coregui/Models/SessionXML.h
index b3392af4c2d4dd2072ebf659293433646bf27e2b..32b37656f4fe9026904774e4749c2bb0f816068c 100644
--- a/GUI/coregui/Models/SessionXML.h
+++ b/GUI/coregui/Models/SessionXML.h
@@ -57,7 +57,7 @@ BA_CORE_API_ void writeItemAndChildItems(QXmlStreamWriter* writer, const Session
 BA_CORE_API_ void writeVariant(QXmlStreamWriter* writer, QVariant variant, int role);
 
 BA_CORE_API_ void readItems(QXmlStreamReader* reader, SessionItem* parent,
-                            QString topTag = QString(), MessageService* messageService = nullptr);
+                            QString topTag = "", MessageService* messageService = nullptr);
 BA_CORE_API_ QString readProperty(QXmlStreamReader* reader, SessionItem* item,
                                   MessageService* messageService = nullptr);
 } // namespace SessionXML
diff --git a/GUI/coregui/Views/ImportDataWidgets/CsvImportAssistant/CsvImportTable.cpp b/GUI/coregui/Views/ImportDataWidgets/CsvImportAssistant/CsvImportTable.cpp
index cb808525344ca090cd333613436c1f45f51eabd7..28a71e3a4f81577e8bef071ce27703a8c21c4491 100644
--- a/GUI/coregui/Views/ImportDataWidgets/CsvImportAssistant/CsvImportTable.cpp
+++ b/GUI/coregui/Views/ImportDataWidgets/CsvImportAssistant/CsvImportTable.cpp
@@ -161,7 +161,7 @@ double CsvImportData::multiplier(CsvImportData::DATA_TYPE type) const
 QString CsvImportData::columnLabel(CsvImportData::DATA_TYPE type) const
 {
     if (m_selected_cols.find(type) == m_selected_cols.end())
-        return QString();
+        return "";
     return csv::HeaderLabels[m_selected_cols.at(type).name()];
 }
 
diff --git a/GUI/coregui/Views/ImportDataWidgets/RealDataPropertiesWidget.cpp b/GUI/coregui/Views/ImportDataWidgets/RealDataPropertiesWidget.cpp
index 5d93d96352f05e072dbeb6beb6011e5fb6754e05..2c8681b476319e694113e273c7737193446bf929 100644
--- a/GUI/coregui/Views/ImportDataWidgets/RealDataPropertiesWidget.cpp
+++ b/GUI/coregui/Views/ImportDataWidgets/RealDataPropertiesWidget.cpp
@@ -143,7 +143,7 @@ void RealDataPropertiesWidget::onInstrumentMapUpdate()
         m_instrumentCombo->setCurrentIndex(index);
     } else {
         // instrument corresponding to m_current_id was deleted
-        m_current_id = QString();
+        m_current_id = "";
         m_instrumentCombo->setCurrentIndex(0);
     }
     setComboConnected(true);
diff --git a/GUI/coregui/Views/InfoWidgets/ComboSelectorDialog.h b/GUI/coregui/Views/InfoWidgets/ComboSelectorDialog.h
index d2a7a462e9e3856e89e6b99f36421e60e8ec00ed..0f54f51aa299f8b647100ba0946988b8e3948701 100644
--- a/GUI/coregui/Views/InfoWidgets/ComboSelectorDialog.h
+++ b/GUI/coregui/Views/InfoWidgets/ComboSelectorDialog.h
@@ -31,7 +31,7 @@ class BA_CORE_API_ ComboSelectorDialog : public QDialog
 public:
     ComboSelectorDialog(QWidget* parent = 0);
 
-    void addItems(const QStringList& selection, const QString& currentItem = QString());
+    void addItems(const QStringList& selection, const QString& currentItem = "");
     void setTextTop(const QString& text);
     void setTextBottom(const QString& text);
 
diff --git a/GUI/coregui/Views/InfoWidgets/ProjectLoadWarningDialog.h b/GUI/coregui/Views/InfoWidgets/ProjectLoadWarningDialog.h
index 730a5c6fdb9ad3a2542f2426c0cea5dca0c1fa42..cbad9c1290a5bac16ae6e5cd9752363d8bf9d2cd 100644
--- a/GUI/coregui/Views/InfoWidgets/ProjectLoadWarningDialog.h
+++ b/GUI/coregui/Views/InfoWidgets/ProjectLoadWarningDialog.h
@@ -34,7 +34,7 @@ class BA_CORE_API_ ProjectLoadWarningDialog : public QDialog
 
 public:
     ProjectLoadWarningDialog(QWidget* parent, const MessageService* messageService = 0,
-                             const QString& documentVersion = QString());
+                             const QString& documentVersion = "");
 
 private:
     QWidget* createTopPanel();
diff --git a/GUI/coregui/Views/InfoWidgets/PythonSyntaxHighlighter.h b/GUI/coregui/Views/InfoWidgets/PythonSyntaxHighlighter.h
index a9cc419f2c8adfa13cd49914d01b7f67235eb80b..004b445dba0dd8e66140f8f51658d19c0cf5bf77 100644
--- a/GUI/coregui/Views/InfoWidgets/PythonSyntaxHighlighter.h
+++ b/GUI/coregui/Views/InfoWidgets/PythonSyntaxHighlighter.h
@@ -82,7 +82,7 @@ private:
     bool matchMultiline(const QString& text, const QRegExp& delimiter, const int inState,
                         const QTextCharFormat& style);
     const QTextCharFormat getTextCharFormat(const QString& colorName,
-                                            const QString& style = QString());
+                                            const QString& style = "");
 
     QList<HighlightingRule> rules;
     QRegExp triSingleQuote;
diff --git a/GUI/coregui/Views/IntensityDataWidgets/SavePlotAssistant.cpp b/GUI/coregui/Views/IntensityDataWidgets/SavePlotAssistant.cpp
index 22c23511213507cfc1ca036c615a0065fda9c696..a4ce2e4c14c1099a69cb104c3d53378b2702b40a 100644
--- a/GUI/coregui/Views/IntensityDataWidgets/SavePlotAssistant.cpp
+++ b/GUI/coregui/Views/IntensityDataWidgets/SavePlotAssistant.cpp
@@ -138,7 +138,7 @@ QString SavePlotAssistant::getExtensionFromFilterName(const QString& filterName)
             return m_formats[i].m_file_extention;
         }
     }
-    return QString();
+    return "";
 }
 
 bool SavePlotAssistant::isPngFile(const QString& fileName) const
diff --git a/GUI/coregui/Views/MaskWidgets/MaskDrawingContext.cpp b/GUI/coregui/Views/MaskWidgets/MaskDrawingContext.cpp
index 57fe23a11cf5fed0bed62b284c957a97c82337af..63132236fc40e7fdef38c8ec4811f9b8e63d91ed 100644
--- a/GUI/coregui/Views/MaskWidgets/MaskDrawingContext.cpp
+++ b/GUI/coregui/Views/MaskWidgets/MaskDrawingContext.cpp
@@ -128,7 +128,7 @@ QString MaskDrawingContext::activityToModelType() const
         return "EllipseMask";
     if (isROIMode())
         return "RegionOfInterest";
-    return QString();
+    return "";
 }
 
 //! Returns model row corresponding to given activity. All shapes, except ROI, will be added
diff --git a/GUI/coregui/Views/PropertyEditor/ComponentEditor.h b/GUI/coregui/Views/PropertyEditor/ComponentEditor.h
index 8851cb0f53fd1da1678e7aee850eb577430ccaee..fc149e444b7db9e8cb3ab0bf8bfea8e15daf6471 100644
--- a/GUI/coregui/Views/PropertyEditor/ComponentEditor.h
+++ b/GUI/coregui/Views/PropertyEditor/ComponentEditor.h
@@ -50,7 +50,7 @@ public:
     };
     Q_DECLARE_FLAGS(EditorType, EditorFlags)
 
-    ComponentEditor(EditorType editorType = HeaderTree, const QString& title = QString());
+    ComponentEditor(EditorType editorType = HeaderTree, const QString& title = "");
 
     void setItem(SessionItem* item);
     void clearEditor();
diff --git a/GUI/coregui/Views/PropertyEditor/PropertyEditorFactory.cpp b/GUI/coregui/Views/PropertyEditor/PropertyEditorFactory.cpp
index a891374b79580c707e86a1488654632b21d08a74..87c42c9ebdda2e34ae235c1944cd4397372307df 100644
--- a/GUI/coregui/Views/PropertyEditor/PropertyEditorFactory.cpp
+++ b/GUI/coregui/Views/PropertyEditor/PropertyEditorFactory.cpp
@@ -98,7 +98,7 @@ QString PropertyEditorFactory::toString(const QModelIndex& index)
                          : QString::number(item->value().toDouble(), 'f', item->decimals());
     }
 
-    return QString();
+    return "";
 }
 
 QWidget* PropertyEditorFactory::CreateEditor(const SessionItem& item, QWidget* parent)
diff --git a/GUI/coregui/Views/SampleDesigner/ILayerView.h b/GUI/coregui/Views/SampleDesigner/ILayerView.h
index 21ef053ffd8950ce5709eee7bbf3ba57aa485f0e..d6ae86dd74ebdc97bbc901e257c627a04f0ec289 100644
--- a/GUI/coregui/Views/SampleDesigner/ILayerView.h
+++ b/GUI/coregui/Views/SampleDesigner/ILayerView.h
@@ -31,7 +31,7 @@ public:
 
     int type() const { return ViewTypes::LAYER; }
 
-    virtual QString getLabel() const { return QString(); }
+    virtual QString getLabel() const { return ""; }
 
     void updateLabel();
 
diff --git a/GUI/coregui/Views/SimulationWidgets/PythonScriptWidget.h b/GUI/coregui/Views/SimulationWidgets/PythonScriptWidget.h
index a3cc7fbf0976f1d2da12947b771fada526d816c2..900c0ae99e26990fb4ab204501f2e7732a3c1cf9 100644
--- a/GUI/coregui/Views/SimulationWidgets/PythonScriptWidget.h
+++ b/GUI/coregui/Views/SimulationWidgets/PythonScriptWidget.h
@@ -38,7 +38,7 @@ public:
     void generatePythonScript(const MultiLayerItem* sampleItem,
                               const InstrumentItem* instrumentItem,
                               const SimulationOptionsItem* optionItem = 0,
-                              const QString& outputDir = QString());
+                              const QString& outputDir = "");
 
 private slots:
     void onExportToFileButton();
diff --git a/GUI/coregui/Views/widgetbox/qdesigner_formbuilder_p.h b/GUI/coregui/Views/widgetbox/qdesigner_formbuilder_p.h
index 20c200da0c3842cf896295ca8f8e6670cc8acb5f..9631accda4f6623beac5e86de4a270043cf43cc7 100644
--- a/GUI/coregui/Views/widgetbox/qdesigner_formbuilder_p.h
+++ b/GUI/coregui/Views/widgetbox/qdesigner_formbuilder_p.h
@@ -106,7 +106,7 @@ public:
                                   const DeviceProfile& deviceProfile, QString* errorMessage);
     // Convenience that pops up message boxes in case of failures.
     static QWidget* createPreview(const QDesignerFormWindowInterface* fw,
-                                  const QString& styleName = QString());
+                                  const QString& styleName = "");
     //  Create a preview widget (for integrations) or return 0. The widget has to be embedded into a
     //  main window.
     static QWidget* createPreview(const QDesignerFormWindowInterface* fw, const QString& styleName,
@@ -117,8 +117,8 @@ public:
 
     // Create a preview image
     static QPixmap createPreviewPixmap(const QDesignerFormWindowInterface* fw,
-                                       const QString& styleName = QString(),
-                                       const QString& appStyleSheet = QString());
+                                       const QString& styleName = "",
+                                       const QString& appStyleSheet = "");
 
 protected:
     using QFormBuilder::create;
diff --git a/GUI/coregui/Views/widgetbox/qdesigner_utils_p.h b/GUI/coregui/Views/widgetbox/qdesigner_utils_p.h
index bbb258d03cd06f473af324eb649b70f0982ea894..acbc7a3deaa956476b46adb76ae924a6e7d9d013 100644
--- a/GUI/coregui/Views/widgetbox/qdesigner_utils_p.h
+++ b/GUI/coregui/Views/widgetbox/qdesigner_utils_p.h
@@ -331,8 +331,8 @@ class QDESIGNER_SHARED_EXPORT PropertySheetTranslatableData
 {
 protected:
     PropertySheetTranslatableData(bool translatable = true,
-                                  const QString& disambiguation = QString(),
-                                  const QString& comment = QString());
+                                  const QString& disambiguation = "",
+                                  const QString& comment = "");
     bool equals(const PropertySheetTranslatableData& rhs) const;
 
 public:
@@ -353,9 +353,9 @@ private:
 class QDESIGNER_SHARED_EXPORT PropertySheetStringValue : public PropertySheetTranslatableData
 {
 public:
-    PropertySheetStringValue(const QString& value = QString(), bool translatable = true,
-                             const QString& disambiguation = QString(),
-                             const QString& comment = QString());
+    PropertySheetStringValue(const QString& value = "", bool translatable = true,
+                             const QString& disambiguation = "",
+                             const QString& comment = "");
 
     bool operator==(const PropertySheetStringValue& other) const { return equals(other); }
     bool operator!=(const PropertySheetStringValue& other) const { return !equals(other); }
@@ -374,8 +374,8 @@ class QDESIGNER_SHARED_EXPORT PropertySheetStringListValue : public PropertyShee
 {
 public:
     PropertySheetStringListValue(const QStringList& value = QStringList(), bool translatable = true,
-                                 const QString& disambiguation = QString(),
-                                 const QString& comment = QString());
+                                 const QString& disambiguation = "",
+                                 const QString& comment = "");
 
     bool operator==(const PropertySheetStringListValue& other) const { return equals(other); }
     bool operator!=(const PropertySheetStringListValue& other) const { return !equals(other); }
@@ -395,12 +395,12 @@ class QDESIGNER_SHARED_EXPORT PropertySheetKeySequenceValue : public PropertyShe
 public:
     PropertySheetKeySequenceValue(const QKeySequence& value = QKeySequence(),
                                   bool translatable = true,
-                                  const QString& disambiguation = QString(),
-                                  const QString& comment = QString());
+                                  const QString& disambiguation = "",
+                                  const QString& comment = "");
     PropertySheetKeySequenceValue(const QKeySequence::StandardKey& standardKey,
                                   bool translatable = true,
-                                  const QString& disambiguation = QString(),
-                                  const QString& comment = QString());
+                                  const QString& disambiguation = "",
+                                  const QString& comment = "");
 
     bool operator==(const PropertySheetKeySequenceValue& other) const { return equals(other); }
     bool operator!=(const PropertySheetKeySequenceValue& other) const { return !equals(other); }
diff --git a/GUI/coregui/Views/widgetbox/qdesigner_widgetbox_p.h b/GUI/coregui/Views/widgetbox/qdesigner_widgetbox_p.h
index 0a40765351f7f65ff3f2695346148100b53d1b83..196aaf98c6cc6b0392f3df3f9d775d8536fbaa89 100644
--- a/GUI/coregui/Views/widgetbox/qdesigner_widgetbox_p.h
+++ b/GUI/coregui/Views/widgetbox/qdesigner_widgetbox_p.h
@@ -81,11 +81,11 @@ public:
     // Convenience to access the widget box icon of a widget. Empty category
     // matches all
     virtual QIcon iconForWidget(const QString& className,
-                                const QString& category = QString()) const = 0;
+                                const QString& category = "") const = 0;
 
     // Convenience to find a widget by class name. Empty category matches all
     static bool findWidget(const QDesignerWidgetBoxInterface* wbox, const QString& className,
-                           const QString& category /* = QString()  */, Widget* widgetData);
+                           const QString& category /* = ""  */, Widget* widgetData);
     // Convenience functions to create a DomWidget from widget box xml.
     static DomUI* xmlToUi(const QString& name, const QString& xml, bool insertFakeTopLevel,
                           QString* errorMessage);
diff --git a/GUI/coregui/Views/widgetbox/ui4_p.h b/GUI/coregui/Views/widgetbox/ui4_p.h
index d162e4d4cf0e0778296ee8a984de6814eeef4a5b..da857ca9a995cd6f6ff54d2b47b729e6404af128 100644
--- a/GUI/coregui/Views/widgetbox/ui4_p.h
+++ b/GUI/coregui/Views/widgetbox/ui4_p.h
@@ -165,7 +165,7 @@ public:
     ~DomUI();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -383,7 +383,7 @@ public:
     ~DomIncludes();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -413,7 +413,7 @@ public:
     ~DomInclude();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -462,7 +462,7 @@ public:
     ~DomResources();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -504,7 +504,7 @@ public:
     ~DomResource();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -541,7 +541,7 @@ public:
     ~DomActionGroup();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -595,7 +595,7 @@ public:
     ~DomAction();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -653,7 +653,7 @@ public:
     ~DomActionRef();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -690,7 +690,7 @@ public:
     ~DomButtonGroup();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -736,7 +736,7 @@ public:
     ~DomButtonGroups();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -766,7 +766,7 @@ public:
     ~DomImages();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -796,7 +796,7 @@ public:
     ~DomImage();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -841,7 +841,7 @@ public:
     ~DomImageData();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -890,7 +890,7 @@ public:
     ~DomCustomWidgets();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -920,7 +920,7 @@ public:
     ~DomHeader();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -957,7 +957,7 @@ public:
     ~DomCustomWidget();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1081,7 +1081,7 @@ public:
     ~DomProperties();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1111,7 +1111,7 @@ public:
     ~DomPropertyData();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1148,7 +1148,7 @@ public:
     ~DomSizePolicyData();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1186,7 +1186,7 @@ public:
     ~DomLayoutDefault();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1235,7 +1235,7 @@ public:
     ~DomLayoutFunction();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1284,7 +1284,7 @@ public:
     ~DomTabStops();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1314,7 +1314,7 @@ public:
     ~DomLayout();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1436,7 +1436,7 @@ public:
     ~DomLayoutItem();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1539,7 +1539,7 @@ public:
     ~DomRow();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1569,7 +1569,7 @@ public:
     ~DomColumn();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1599,7 +1599,7 @@ public:
     ~DomItem();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1657,7 +1657,7 @@ public:
     ~DomWidget();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1790,7 +1790,7 @@ public:
     ~DomSpacer();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1832,7 +1832,7 @@ public:
     ~DomColor();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1888,7 +1888,7 @@ public:
     ~DomGradientStop();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -1933,7 +1933,7 @@ public:
     ~DomGradient();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2119,7 +2119,7 @@ public:
     ~DomBrush();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2174,7 +2174,7 @@ public:
     ~DomColorRole();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2219,7 +2219,7 @@ public:
     ~DomColorGroup();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2253,7 +2253,7 @@ public:
     ~DomPalette();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2300,7 +2300,7 @@ public:
     ~DomFont();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2397,7 +2397,7 @@ public:
     ~DomPoint();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2435,7 +2435,7 @@ public:
     ~DomRect();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2485,7 +2485,7 @@ public:
     ~DomLocale();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2534,7 +2534,7 @@ public:
     ~DomSizePolicy();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2608,7 +2608,7 @@ public:
     ~DomSize();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2646,7 +2646,7 @@ public:
     ~DomDate();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2690,7 +2690,7 @@ public:
     ~DomTime();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2734,7 +2734,7 @@ public:
     ~DomDateTime();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2796,7 +2796,7 @@ public:
     ~DomStringList();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2862,7 +2862,7 @@ public:
     ~DomResourcePixmap();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -2911,7 +2911,7 @@ public:
     ~DomResourceIcon();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3026,7 +3026,7 @@ public:
     ~DomString();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3087,7 +3087,7 @@ public:
     ~DomPointF();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3125,7 +3125,7 @@ public:
     ~DomRectF();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3175,7 +3175,7 @@ public:
     ~DomSizeF();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3213,7 +3213,7 @@ public:
     ~DomChar();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3245,7 +3245,7 @@ public:
     ~DomUrl();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3278,7 +3278,7 @@ public:
     ~DomProperty();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3518,7 +3518,7 @@ public:
     ~DomConnections();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3548,7 +3548,7 @@ public:
     ~DomConnection();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3605,7 +3605,7 @@ public:
     ~DomConnectionHints();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3635,7 +3635,7 @@ public:
     ~DomConnectionHint();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3685,7 +3685,7 @@ public:
     ~DomScript();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3734,7 +3734,7 @@ public:
     ~DomWidgetData();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3764,7 +3764,7 @@ public:
     ~DomDesignerData();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3794,7 +3794,7 @@ public:
     ~DomSlots();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3828,7 +3828,7 @@ public:
     ~DomPropertySpecifications();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
@@ -3861,7 +3861,7 @@ public:
     ~DomStringPropertySpecification();
 
     void read(QXmlStreamReader& reader);
-    void write(QXmlStreamWriter& writer, const QString& tagName = QString()) const;
+    void write(QXmlStreamWriter& writer, const QString& tagName = "") const;
     inline QString text() const { return m_text; }
     inline void setText(const QString& s) { m_text = s; }
 
diff --git a/GUI/coregui/Views/widgetbox/widgetbox.h b/GUI/coregui/Views/widgetbox/widgetbox.h
index 2906dc9db62e015f2d036b35f7bdbc91324840a3..334dccd790de80c47210525995cfdce8977a4cb0 100644
--- a/GUI/coregui/Views/widgetbox/widgetbox.h
+++ b/GUI/coregui/Views/widgetbox/widgetbox.h
@@ -90,7 +90,7 @@ public:
 
     virtual bool loadContents(const QString& contents);
     virtual QIcon iconForWidget(const QString& className,
-                                const QString& category = QString()) const;
+                                const QString& category = "") const;
 
 protected:
     virtual void dragEnterEvent(QDragEnterEvent* event);
diff --git a/GUI/coregui/mainwindow/AutosaveController.cpp b/GUI/coregui/mainwindow/AutosaveController.cpp
index 6f85680625a7f6a309f99c9532fed7f21c4755cf..3dd5ae0db6422f884ffc1e929b4f4ed9773add05 100644
--- a/GUI/coregui/mainwindow/AutosaveController.cpp
+++ b/GUI/coregui/mainwindow/AutosaveController.cpp
@@ -61,7 +61,7 @@ QString AutosaveController::autosaveDir() const
     if (m_document && m_document->hasValidNameAndPath())
         return ProjectUtils::autosaveDir(m_document->projectFileName());
 
-    return QString();
+    return "";
 }
 
 QString AutosaveController::autosaveName() const
@@ -69,7 +69,7 @@ QString AutosaveController::autosaveName() const
     if (m_document && m_document->hasValidNameAndPath())
         return ProjectUtils::autosaveName(m_document->projectFileName());
 
-    return QString();
+    return "";
 }
 
 void AutosaveController::removeAutosaveDir()
diff --git a/GUI/coregui/mainwindow/PyImportAssistant.cpp b/GUI/coregui/mainwindow/PyImportAssistant.cpp
index 3fd969102554a211732d93686709e1ad5d7caac5..1c48fc95aea26a1160acfa829940948c929b4723 100644
--- a/GUI/coregui/mainwindow/PyImportAssistant.cpp
+++ b/GUI/coregui/mainwindow/PyImportAssistant.cpp
@@ -48,7 +48,7 @@ std::string bornagainDir()
 QString getCandidate(const QStringList& funcNames)
 {
     if (funcNames.isEmpty())
-        return QString();
+        return "";
 
     for (auto str : funcNames) {
         QString name = str.toLower();
@@ -149,7 +149,7 @@ QString PyImportAssistant::getPySampleFunctionName(const QString& snippet)
         DetailedMessageBox warning(m_mainWindow, "Python failure", message, details);
         warning.exec();
 
-        return QString();
+        return "";
     }
     QApplication::restoreOverrideCursor();
 
diff --git a/GUI/coregui/mainwindow/newprojectdialog.h b/GUI/coregui/mainwindow/newprojectdialog.h
index 728c51da960a40773e13c88624545a2cd77bfe59..b5f002332314bb11d541f1b2ed287e2e16e19ae5 100644
--- a/GUI/coregui/mainwindow/newprojectdialog.h
+++ b/GUI/coregui/mainwindow/newprojectdialog.h
@@ -26,8 +26,8 @@ class BA_CORE_API_ NewProjectDialog : public QDialog
 {
     Q_OBJECT
 public:
-    NewProjectDialog(QWidget* parent = 0, const QString& workingDirectory = QString(),
-                     const QString& projectName = QString());
+    NewProjectDialog(QWidget* parent = 0, const QString& workingDirectory = "",
+                     const QString& projectName = "");
 
     QString getWorkingDirectory() const;
     void setWorkingDirectory(const QString& text);
diff --git a/GUI/coregui/mainwindow/projectdocument.cpp b/GUI/coregui/mainwindow/projectdocument.cpp
index c8792f077abf5b249a4693822869e4b250ba5369..a50f72652d8addecf283b6a0b1951a8a020d2ea6 100644
--- a/GUI/coregui/mainwindow/projectdocument.cpp
+++ b/GUI/coregui/mainwindow/projectdocument.cpp
@@ -65,7 +65,7 @@ QString ProjectDocument::projectFileName() const
     if (!projectName().isEmpty())
         return projectDir() + "/" + projectName() + projectFileExtension();
     else
-        return QString();
+        return "";
 }
 
 void ProjectDocument::setProjectFileName(const QString& projectFileName)
diff --git a/GUI/coregui/mainwindow/projectdocument.h b/GUI/coregui/mainwindow/projectdocument.h
index 637429bf6112b78701601c51225394b4e4b246b1..8ac9364bc5682f1c99e5e9ad923023e934e7b91e 100644
--- a/GUI/coregui/mainwindow/projectdocument.h
+++ b/GUI/coregui/mainwindow/projectdocument.h
@@ -44,7 +44,7 @@ class BA_CORE_API_ ProjectDocument : public QObject
     Q_OBJECT
 
 public:
-    ProjectDocument(const QString& projectFileName = QString());
+    ProjectDocument(const QString& projectFileName = "");
 
     QString projectName() const;
     void setProjectName(const QString& text);
diff --git a/GUI/coregui/mainwindow/projectmanager.cpp b/GUI/coregui/mainwindow/projectmanager.cpp
index 93e2d3977a0632300f16acc0bf48048dd5dc2c61..8cefae52a00637188b4f95c59355f3d286b23e70 100644
--- a/GUI/coregui/mainwindow/projectmanager.cpp
+++ b/GUI/coregui/mainwindow/projectmanager.cpp
@@ -121,7 +121,7 @@ QString ProjectManager::projectDir() const
     if (m_project_document && m_project_document->hasValidNameAndPath())
         return m_project_document->projectDir();
 
-    return QString();
+    return "";
 }
 
 //! Returns directory name suitable for saving plots.
@@ -360,7 +360,7 @@ QString ProjectManager::acquireProjectFileName()
     NewProjectDialog dialog(m_mainWindow, workingDirectory(), untitledProjectName());
 
     if (dialog.exec() != QDialog::Accepted)
-        return QString();
+        return "";
 
     m_workingDirectory = dialog.getWorkingDirectory();
 
diff --git a/GUI/coregui/mainwindow/projectmanager.h b/GUI/coregui/mainwindow/projectmanager.h
index 6f1a727670d45f44d5b9c973df78fc0965ec0c98..0bef4533d7881bf7c88335f7212fa972017dc98f 100644
--- a/GUI/coregui/mainwindow/projectmanager.h
+++ b/GUI/coregui/mainwindow/projectmanager.h
@@ -55,9 +55,9 @@ public slots:
     void clearRecentProjects();
     void newProject();
     bool closeCurrentProject();
-    bool saveProject(QString projectFileName = QString());
+    bool saveProject(QString projectFileName = "");
     bool saveProjectAs();
-    void openProject(QString fileName = QString());
+    void openProject(QString fileName = "");
 
 private:
     void createNewProject();
diff --git a/GUI/coregui/utils/GUIHelpers.cpp b/GUI/coregui/utils/GUIHelpers.cpp
index 206d3284d4806f5272397ad04a62cb3324a6bfef..23c06bcf537ca22e8bfe08b3c7659ab64fb337d4 100644
--- a/GUI/coregui/utils/GUIHelpers.cpp
+++ b/GUI/coregui/utils/GUIHelpers.cpp
@@ -187,7 +187,7 @@ QString fileDir(const QString& fileName)
     if (info.exists()) {
         return info.dir().path();
     }
-    return QString();
+    return "";
 }
 
 //! Returns base name of file.
diff --git a/GUI/coregui/utils/GUIHelpers.h b/GUI/coregui/utils/GUIHelpers.h
index 5aa1b8d10586dac134690fead8f235527801c8cc..f182845bcc6f317d1ba647db5d595cf588adf2bb 100644
--- a/GUI/coregui/utils/GUIHelpers.h
+++ b/GUI/coregui/utils/GUIHelpers.h
@@ -44,14 +44,14 @@ private:
 };
 
 BA_CORE_API_ void information(QWidget* parent, const QString& title, const QString& text,
-                              const QString& detailedText = QString());
+                              const QString& detailedText = "");
 BA_CORE_API_ void warning(QWidget* parent, const QString& title, const QString& text,
-                          const QString& detailedText = QString());
+                          const QString& detailedText = "");
 BA_CORE_API_ bool question(QWidget* parent, const QString& title, const QString& text,
-                           const QString& detailedText = QString(), const QString& yesText = "&Yes",
+                           const QString& detailedText = "", const QString& yesText = "&Yes",
                            const QString& noText = "&No");
 BA_CORE_API_ bool okToDelete(QWidget* parent, const QString& title, const QString& text,
-                             const QString& detailedText = QString());
+                             const QString& detailedText = "");
 
 BA_CORE_API_ QString getBornAgainVersionString();
 
diff --git a/GUI/coregui/utils/ItemIDFactory.cpp b/GUI/coregui/utils/ItemIDFactory.cpp
index 87b4ac0d34bec94e2bd8ce4cf5488f6d03a2e86c..a4a2e17a3666a5cc425e625112af9e396dbb6db9 100644
--- a/GUI/coregui/utils/ItemIDFactory.cpp
+++ b/GUI/coregui/utils/ItemIDFactory.cpp
@@ -42,7 +42,7 @@ QString ItemIDFactory::getID(SessionItem* existingItem)
     if (instance().ItemtoIDMap.contains(existingItem))
         return instance().ItemtoIDMap.value(existingItem);
     else
-        return QString();
+        return "";
 }
 
 SessionItem* ItemIDFactory::getItem(QString existingID)
diff --git a/GUI/coregui/utils/MessageService.h b/GUI/coregui/utils/MessageService.h
index af5288f590fdbe316dbf50d262b1834ea2e2145c..ccf6bd264a834bc0702548e9dc514f2e38697cea 100644
--- a/GUI/coregui/utils/MessageService.h
+++ b/GUI/coregui/utils/MessageService.h
@@ -41,7 +41,7 @@ public:
 
     QStringList senderList() const;
 
-    int messageCount(const QObject* sender, const QString& message_type = QString()) const;
+    int messageCount(const QObject* sender, const QString& message_type = "") const;
     int warningCount(const QObject* sender = 0) const;
     int errorCount(const QObject* sender = 0) const;