diff --git a/applications/Mapple/dialogs/dialog_properties.cpp b/applications/Mapple/dialogs/dialog_properties.cpp
index 1c8cb4c7..bb2bb34d 100644
--- a/applications/Mapple/dialogs/dialog_properties.cpp
+++ b/applications/Mapple/dialogs/dialog_properties.cpp
@@ -79,13 +79,13 @@ DialogProperties::DialogProperties(MainWindow *window)
     margins.setLeft(7);
     lineEditNewPropertyName->setTextMargins(margins);
 
-    connect(comboBoxCommand, SIGNAL(currentIndexChanged(const QString &)), this,
+    connect(comboBoxCommand, SIGNAL(currentTextChanged(const QString &)), this,
             SLOT(commandChanged(const QString &)));
-    connect(comboBoxModels, SIGNAL(currentIndexChanged(const QString &)), this,
+    connect(comboBoxModels, SIGNAL(currentTextChanged(const QString &)), this,
             SLOT(modelChanged(const QString &)));
-    connect(comboBoxPropertyLocation, SIGNAL(currentIndexChanged(const QString &)), this,
+    connect(comboBoxPropertyLocation, SIGNAL(currentTextChanged(const QString &)), this,
             SLOT(locationChanged(const QString &)));
-    connect(comboBoxPropertyName, SIGNAL(currentIndexChanged(const QString &)), this,
+    connect(comboBoxPropertyName, SIGNAL(currentTextChanged(const QString &)), this,
             SLOT(propertyChanged(const QString &)));
     connect(updateButton, SIGNAL(clicked()), this, SLOT(updateProperties()));
     connect(applyButton, SIGNAL(clicked()), this, SLOT(applyCommand()));
@@ -176,7 +176,7 @@ void DialogProperties::modelChanged(const QString &text) {
     if (!model)
         return;
 
-    disconnect(comboBoxPropertyLocation, SIGNAL(currentIndexChanged(const QString &)), this,
+    disconnect(comboBoxPropertyLocation, SIGNAL(currentTextChanged(const QString &)), this,
                SLOT(locationChanged(const QString &)));
 
     if (dynamic_cast<SurfaceMesh *>(model)) {
@@ -203,7 +203,7 @@ void DialogProperties::modelChanged(const QString &text) {
 
     locationChanged(comboBoxPropertyLocation->currentText());
 
-    connect(comboBoxPropertyLocation, SIGNAL(currentIndexChanged(const QString &)), this,
+    connect(comboBoxPropertyLocation, SIGNAL(currentTextChanged(const QString &)), this,
             SLOT(locationChanged(const QString &)));
 }
 
@@ -1127,7 +1127,7 @@ void DialogProperties::updateProperties() {
     const std::string &model_text = comboBoxModels->currentText().toStdString();
     bool model_text_has_match = false;
 
-    disconnect(comboBoxModels, SIGNAL(currentIndexChanged(const QString &)), this,
+    disconnect(comboBoxModels, SIGNAL(currentTextChanged(const QString &)), this,
                SLOT(modelChanged(const QString &)));
     comboBoxModels->clear();
 
@@ -1151,7 +1151,7 @@ void DialogProperties::updateProperties() {
     }
     modelChanged(comboBoxModels->currentText());
 
-    connect(comboBoxModels, SIGNAL(currentIndexChanged(QString)), this, SLOT(modelChanged(QString)));
+    connect(comboBoxModels, SIGNAL(currentTextChanged(const QString&)), this, SLOT(modelChanged(const QString&)));
 }
 
 
diff --git a/applications/Mapple/dialogs/dialog_surface_mesh_remeshing.cpp b/applications/Mapple/dialogs/dialog_surface_mesh_remeshing.cpp
index 8b401b27..8d5212cc 100644
--- a/applications/Mapple/dialogs/dialog_surface_mesh_remeshing.cpp
+++ b/applications/Mapple/dialogs/dialog_surface_mesh_remeshing.cpp
@@ -46,7 +46,7 @@ DialogSurfaceMeshRemeshing::DialogSurfaceMeshRemeshing(MainWindow *window)
     comboBoxScheme->addItem("Adaptive Remeshing");
     comboBoxScheme->setCurrentIndex(0);
 
-    connect(comboBoxScheme, SIGNAL(currentIndexChanged(const QString &)),this, SLOT(setRemeshingScheme(const QString &)));
+    connect(comboBoxScheme, SIGNAL(currentTextChanged(const QString &)),this, SLOT(setRemeshingScheme(const QString &)));
 
     layout()->setSizeConstraint(QLayout::SetFixedSize);
     connect(okButton, SIGNAL(clicked()), this, SLOT(apply()));
diff --git a/applications/Mapple/dialogs/dialog_surface_mesh_smoothing.cpp b/applications/Mapple/dialogs/dialog_surface_mesh_smoothing.cpp
index ec0d692d..68852997 100644
--- a/applications/Mapple/dialogs/dialog_surface_mesh_smoothing.cpp
+++ b/applications/Mapple/dialogs/dialog_surface_mesh_smoothing.cpp
@@ -46,7 +46,7 @@ DialogSurfaceMeshSmoothing::DialogSurfaceMeshSmoothing(MainWindow *window)
     comboBoxScheme->addItem("Implicit Smoothing");
     comboBoxScheme->setCurrentIndex(0);
 
-    connect(comboBoxScheme, SIGNAL(currentIndexChanged(const QString &)),this, SLOT(setSmoothingScheme(const QString &)));
+    connect(comboBoxScheme, SIGNAL(currentTextChanged(const QString &)),this, SLOT(setSmoothingScheme(const QString &)));
 
     layout()->setSizeConstraint(QLayout::SetFixedSize);
     connect(okButton, SIGNAL(clicked()), this, SLOT(apply()));
diff --git a/applications/Mapple/main.cpp b/applications/Mapple/main.cpp
index f04d3ff7..ff79fca7 100644
--- a/applications/Mapple/main.cpp
+++ b/applications/Mapple/main.cpp
@@ -38,7 +38,6 @@
 
 #include <QStyleFactory>
 #include <QSurfaceFormat>
-#include <QGLFormat>
 #include <QElapsedTimer>
 #include <QException>
 
@@ -123,8 +122,9 @@ int main(int argc, char *argv[]) {
     //QApplication::setAttribute(Qt::AA_UseDesktopOpenGL);
 
     QApplication::setAttribute(Qt::AA_ShareOpenGLContexts);
+
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 6, 0) && (QT_VERSION < QT_VERSION_CHECK(6, 0, 0)))
     QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
-#if (defined(Q_OS_WIN) && QT_VERSION >= QT_VERSION_CHECK(5, 6, 0))
     QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
 #endif
 
@@ -164,15 +164,6 @@ int main(int argc, char *argv[]) {
     }
 #endif
 
-    if (!QGLFormat::hasOpenGL()) {
-        LOG(ERROR) << "Mapple needs OpenGL to run";
-        return EXIT_FAILURE;
-    }
-    if ((QGLFormat::openGLVersionFlags() & QGLFormat::OpenGL_Version_3_2) == 0) {
-        LOG(ERROR) << "Mapple needs OpenGL 3.2 at least to run";
-        return EXIT_FAILURE;
-    }
-
     try {
         MainWindow win;
         if (!logging::log_file().empty())
diff --git a/applications/Mapple/main_window.cpp b/applications/Mapple/main_window.cpp
index 92ca58d8..bf7c6a9c 100644
--- a/applications/Mapple/main_window.cpp
+++ b/applications/Mapple/main_window.cpp
@@ -37,7 +37,7 @@
 #include <QSettings>
 #include <QMessageBox>
 #include <QColorDialog>
-#include <QCoreApplication>
+#include <QActionGroup>
 #include <QLabel>
 #include <QPushButton>
 #include <QProgressBar>
@@ -835,12 +835,14 @@ void MainWindow::restoreCameraStateFromFile() {
 bool MainWindow::okToContinue()
 {
     if (isWindowModified()) {
-        int r = QMessageBox::warning(this, tr("Mapple"),
-            tr("The model has been modified.\n"
-            "Do you want to save your changes?"),
-            QMessageBox::Yes | QMessageBox::Default,
-            QMessageBox::No,
-            QMessageBox::Cancel | QMessageBox::Escape);
+        QMessageBox::StandardButton r = QMessageBox::warning(
+             this,
+             tr("Mapple"),
+             tr("The model has been modified.\n"
+                "Do you want to save your changes?"),
+             QMessageBox::Yes | QMessageBox::No | QMessageBox::Cancel,
+             QMessageBox::Yes
+         );
         if (r == QMessageBox::Yes)
             return onSave();
         else if (r == QMessageBox::Cancel)
diff --git a/applications/Mapple/widgets/widget_drawable_lines.cpp b/applications/Mapple/widgets/widget_drawable_lines.cpp
index ef834227..969634c2 100644
--- a/applications/Mapple/widgets/widget_drawable_lines.cpp
+++ b/applications/Mapple/widgets/widget_drawable_lines.cpp
@@ -65,7 +65,7 @@ WidgetLinesDrawable::WidgetLinesDrawable(QWidget *parent)
 
 void WidgetLinesDrawable::connectAll() {
     // which drawable
-    connect(ui_->comboBoxDrawables, SIGNAL(currentIndexChanged(const QString &)),
+    connect(ui_->comboBoxDrawables, SIGNAL(currentTextChanged(const QString &)),
             this, SLOT(setActiveDrawable(const QString &)));
 
     // visible
@@ -75,11 +75,11 @@ void WidgetLinesDrawable::connectAll() {
     connect(ui_->doubleSpinBoxLineWidth, SIGNAL(valueChanged(double)), this, SLOT(setLineWidth(double)));
 
     // imposter
-    connect(ui_->comboBoxImposterStyle, SIGNAL(currentIndexChanged(const QString &)),
+    connect(ui_->comboBoxImposterStyle, SIGNAL(currentTextChanged(const QString &)),
             this, SLOT(setImposterStyle(const QString &)));
 
     // color scheme
-    connect(ui_->comboBoxColorScheme, SIGNAL(currentIndexChanged(const QString &)),
+    connect(ui_->comboBoxColorScheme, SIGNAL(currentTextChanged(const QString &)),
             this, SLOT(setColorScheme(const QString &)));
 
     // default color
@@ -99,7 +99,7 @@ void WidgetLinesDrawable::connectAll() {
     connect(ui_->doubleSpinBoxScalarFieldClampUpper, SIGNAL(valueChanged(double)), this, SLOT(setScalarFieldClampUpper(double)));
 
     // vector field
-    connect(ui_->comboBoxVectorField, SIGNAL(currentIndexChanged(const QString&)), this,
+    connect(ui_->comboBoxVectorField, SIGNAL(currentTextChanged(const QString&)), this,
             SLOT(setVectorField(const QString&)));
     connect(ui_->doubleSpinBoxVectorFieldScale, SIGNAL(valueChanged(double)), this, SLOT(setVectorFieldScale(double)));
 }
@@ -107,7 +107,7 @@ void WidgetLinesDrawable::connectAll() {
 
 void WidgetLinesDrawable::disconnectAll() {
     // which drawable
-    disconnect(ui_->comboBoxDrawables, SIGNAL(currentIndexChanged(const QString &)),
+    disconnect(ui_->comboBoxDrawables, SIGNAL(currentTextChanged(const QString &)),
                this, SLOT(setActiveDrawable(const QString &)));
 
     // visible
@@ -117,11 +117,11 @@ void WidgetLinesDrawable::disconnectAll() {
     disconnect(ui_->doubleSpinBoxLineWidth, SIGNAL(valueChanged(double)), this, SLOT(setLineWidth(double)));
 
     // imposter
-    disconnect(ui_->comboBoxImposterStyle, SIGNAL(currentIndexChanged(const QString &)),
+    disconnect(ui_->comboBoxImposterStyle, SIGNAL(currentTextChanged(const QString &)),
                this, SLOT(setImposterStyle(const QString &)));
 
     // color scheme
-    disconnect(ui_->comboBoxColorScheme, SIGNAL(currentIndexChanged(const QString &)),
+    disconnect(ui_->comboBoxColorScheme, SIGNAL(currentTextChanged(const QString &)),
                this, SLOT(setColorScheme(const QString &)));
 
     // default color
@@ -141,7 +141,7 @@ void WidgetLinesDrawable::disconnectAll() {
     disconnect(ui_->doubleSpinBoxScalarFieldClampUpper, SIGNAL(valueChanged(double)), this, SLOT(setScalarFieldClampUpper(double)));
 
     // vector field
-    disconnect(ui_->comboBoxVectorField, SIGNAL(currentIndexChanged(const QString&)), this, SLOT(setVectorField(const QString&)));
+    disconnect(ui_->comboBoxVectorField, SIGNAL(currentTextChanged(const QString&)), this, SLOT(setVectorField(const QString&)));
     disconnect(ui_->doubleSpinBoxVectorFieldScale, SIGNAL(valueChanged(double)), this, SLOT(setVectorFieldScale(double)));
 }
 
diff --git a/applications/Mapple/widgets/widget_drawable_points.cpp b/applications/Mapple/widgets/widget_drawable_points.cpp
index ebcf469c..c75bd3ab 100644
--- a/applications/Mapple/widgets/widget_drawable_points.cpp
+++ b/applications/Mapple/widgets/widget_drawable_points.cpp
@@ -67,7 +67,7 @@ WidgetPointsDrawable::WidgetPointsDrawable(QWidget *parent)
 
 void WidgetPointsDrawable::connectAll() {
     // which drawable
-    connect(ui_->comboBoxDrawables, SIGNAL(currentIndexChanged(const QString &)),
+    connect(ui_->comboBoxDrawables, SIGNAL(currentTextChanged(const QString &)),
             this, SLOT(setActiveDrawable(const QString &)));
 
     // visible
@@ -77,15 +77,15 @@ void WidgetPointsDrawable::connectAll() {
     connect(ui_->doubleSpinBoxPointSize, SIGNAL(valueChanged(double)), this, SLOT(setPointSize(double)));
 
     // imposter
-    connect(ui_->comboBoxImposterStyle, SIGNAL(currentIndexChanged(const QString &)),
+    connect(ui_->comboBoxImposterStyle, SIGNAL(currentTextChanged(const QString &)),
             this, SLOT(setImposterStyle(const QString &)));
 
     // lighting
-    connect(ui_->comboBoxLightingOptions, SIGNAL(currentIndexChanged(const QString &)),
+    connect(ui_->comboBoxLightingOptions, SIGNAL(currentTextChanged(const QString &)),
             this, SLOT(setLighting(const QString &)));
 
     // color scheme
-    connect(ui_->comboBoxColorScheme, SIGNAL(currentIndexChanged(const QString &)),
+    connect(ui_->comboBoxColorScheme, SIGNAL(currentTextChanged(const QString &)),
             this, SLOT(setColorScheme(const QString &)));
 
     // default color
@@ -109,7 +109,7 @@ void WidgetPointsDrawable::connectAll() {
     connect(ui_->doubleSpinBoxScalarFieldClampUpper, SIGNAL(valueChanged(double)), this, SLOT(setScalarFieldClampUpper(double)));
 
     // vector field
-    connect(ui_->comboBoxVectorField, SIGNAL(currentIndexChanged(const QString&)), this,
+    connect(ui_->comboBoxVectorField, SIGNAL(currentTextChanged(const QString&)), this,
             SLOT(setVectorField(const QString&)));
     connect(ui_->doubleSpinBoxVectorFieldScale, SIGNAL(valueChanged(double)), this, SLOT(setVectorFieldScale(double)));
 }
@@ -117,7 +117,7 @@ void WidgetPointsDrawable::connectAll() {
 
 void WidgetPointsDrawable::disconnectAll() {
     // which drawable
-    disconnect(ui_->comboBoxDrawables, SIGNAL(currentIndexChanged(const QString &)),
+    disconnect(ui_->comboBoxDrawables, SIGNAL(currentTextChanged(const QString &)),
                this, SLOT(setActiveDrawable(const QString &)));
 
     // visible
@@ -127,15 +127,15 @@ void WidgetPointsDrawable::disconnectAll() {
     disconnect(ui_->doubleSpinBoxPointSize, SIGNAL(valueChanged(double)), this, SLOT(setPointSize(double)));
 
     // imposter
-    disconnect(ui_->comboBoxImposterStyle, SIGNAL(currentIndexChanged(const QString &)),
+    disconnect(ui_->comboBoxImposterStyle, SIGNAL(currentTextChanged(const QString &)),
                this, SLOT(setImposterStyle(const QString &)));
 
     // lighting
-    disconnect(ui_->comboBoxLightingOptions, SIGNAL(currentIndexChanged(const QString &)),
+    disconnect(ui_->comboBoxLightingOptions, SIGNAL(currentTextChanged(const QString &)),
                this, SLOT(setLighting(const QString &)));
 
     // color scheme
-    disconnect(ui_->comboBoxColorScheme, SIGNAL(currentIndexChanged(const QString &)),
+    disconnect(ui_->comboBoxColorScheme, SIGNAL(currentTextChanged(const QString &)),
                this, SLOT(setColorScheme(const QString &)));
 
     // default color
@@ -159,7 +159,7 @@ void WidgetPointsDrawable::disconnectAll() {
     disconnect(ui_->doubleSpinBoxScalarFieldClampUpper, SIGNAL(valueChanged(double)), this, SLOT(setScalarFieldClampUpper(double)));
 
     // vector field
-    disconnect(ui_->comboBoxVectorField, SIGNAL(currentIndexChanged(const QString&)), this, SLOT(setVectorField(const QString&)));
+    disconnect(ui_->comboBoxVectorField, SIGNAL(currentTextChanged(const QString&)), this, SLOT(setVectorField(const QString&)));
     disconnect(ui_->doubleSpinBoxVectorFieldScale, SIGNAL(valueChanged(double)), this, SLOT(setVectorFieldScale(double)));
 }
 
diff --git a/applications/Mapple/widgets/widget_drawable_triangles.cpp b/applications/Mapple/widgets/widget_drawable_triangles.cpp
index 0ce476a3..83de5a2d 100644
--- a/applications/Mapple/widgets/widget_drawable_triangles.cpp
+++ b/applications/Mapple/widgets/widget_drawable_triangles.cpp
@@ -69,7 +69,7 @@ WidgetTrianglesDrawable::WidgetTrianglesDrawable(QWidget *parent)
 
 void WidgetTrianglesDrawable::connectAll() {
     // which drawable
-    connect(ui_->comboBoxDrawables, SIGNAL(currentIndexChanged(const QString &)),this, SLOT(setActiveDrawable(const QString &)));
+    connect(ui_->comboBoxDrawables, SIGNAL(currentTextChanged(const QString &)),this, SLOT(setActiveDrawable(const QString &)));
 
     // visible
     connect(ui_->checkBoxVisible, SIGNAL(toggled(bool)), this, SLOT(setDrawableVisible(bool)));
@@ -78,10 +78,10 @@ void WidgetTrianglesDrawable::connectAll() {
     connect(ui_->checkBoxPhongShading, SIGNAL(toggled(bool)), this, SLOT(setPhongShading(bool)));
 
     // lighting
-    connect(ui_->comboBoxLightingOptions, SIGNAL(currentIndexChanged(const QString &)),this, SLOT(setLighting(const QString &)));
+    connect(ui_->comboBoxLightingOptions, SIGNAL(currentTextChanged(const QString &)),this, SLOT(setLighting(const QString &)));
 
     // color scheme
-    connect(ui_->comboBoxColorScheme, SIGNAL(currentIndexChanged(const QString &)),this, SLOT(setColorScheme(const QString &)));
+    connect(ui_->comboBoxColorScheme, SIGNAL(currentTextChanged(const QString &)),this, SLOT(setColorScheme(const QString &)));
 
     // default color
     connect(ui_->toolButtonDefaultColor, SIGNAL(clicked()), this, SLOT(setDefaultColor()));
@@ -112,14 +112,14 @@ void WidgetTrianglesDrawable::connectAll() {
     connect(ui_->doubleSpinBoxScalarFieldClampUpper, SIGNAL(valueChanged(double)), this, SLOT(setScalarFieldClampUpper(double)));
 
     // vector field
-    connect(ui_->comboBoxVectorField, SIGNAL(currentIndexChanged(const QString&)), this, SLOT(setVectorField(const QString&)));
+    connect(ui_->comboBoxVectorField, SIGNAL(currentTextChanged(const QString&)), this, SLOT(setVectorField(const QString&)));
     connect(ui_->doubleSpinBoxVectorFieldScale, SIGNAL(valueChanged(double)), this, SLOT(setVectorFieldScale(double)));
 }
 
 
 void WidgetTrianglesDrawable::disconnectAll() {
     // which drawable
-    disconnect(ui_->comboBoxDrawables, SIGNAL(currentIndexChanged(const QString &)),this, SLOT(setActiveDrawable(const QString &)));
+    disconnect(ui_->comboBoxDrawables, SIGNAL(currentTextChanged(const QString &)),this, SLOT(setActiveDrawable(const QString &)));
 
     // visible
     disconnect(ui_->checkBoxVisible, SIGNAL(toggled(bool)), this, SLOT(setDrawableVisible(bool)));
@@ -128,10 +128,10 @@ void WidgetTrianglesDrawable::disconnectAll() {
     disconnect(ui_->checkBoxPhongShading, SIGNAL(toggled(bool)), this, SLOT(setPhongShading(bool)));
 
     // lighting
-    disconnect(ui_->comboBoxLightingOptions, SIGNAL(currentIndexChanged(const QString &)),this, SLOT(setLighting(const QString &)));
+    disconnect(ui_->comboBoxLightingOptions, SIGNAL(currentTextChanged(const QString &)),this, SLOT(setLighting(const QString &)));
 
     // color scheme
-    disconnect(ui_->comboBoxColorScheme, SIGNAL(currentIndexChanged(const QString &)),this, SLOT(setColorScheme(const QString &)));
+    disconnect(ui_->comboBoxColorScheme, SIGNAL(currentTextChanged(const QString &)),this, SLOT(setColorScheme(const QString &)));
 
     // default color
     disconnect(ui_->toolButtonDefaultColor, SIGNAL(clicked()), this, SLOT(setDefaultColor()));
@@ -162,7 +162,7 @@ void WidgetTrianglesDrawable::disconnectAll() {
     disconnect(ui_->doubleSpinBoxScalarFieldClampUpper, SIGNAL(valueChanged(double)), this, SLOT(setScalarFieldClampUpper(double)));
 
     // vector field
-    disconnect(ui_->comboBoxVectorField, SIGNAL(currentIndexChanged(const QString&)), this, SLOT(setVectorField(const QString&)));
+    disconnect(ui_->comboBoxVectorField, SIGNAL(currentTextChanged(const QString&)), this, SLOT(setVectorField(const QString&)));
     disconnect(ui_->doubleSpinBoxVectorFieldScale, SIGNAL(valueChanged(double)), this, SLOT(setVectorFieldScale(double)));
 }
 
diff --git a/easy3d/algo/CMakeLists.txt b/easy3d/algo/CMakeLists.txt
index a0b95f4d..86b5dcbc 100755
--- a/easy3d/algo/CMakeLists.txt
+++ b/easy3d/algo/CMakeLists.txt
@@ -80,6 +80,9 @@ add_module(${module} "${${module}_headers}" "${${module}_sources}" "${private_de
 target_include_directories(easy3d_${module} PRIVATE ${Easy3D_THIRD_PARTY}/eigen ${Easy3D_THIRD_PARTY}/ransac)
 
 # It's "Boost", not "BOOST" or "boost". Case matters.
+if (POLICY CMP0167)
+    cmake_policy(SET CMP0167 NEW)
+endif ()
 find_package(Boost COMPONENTS graph)
 if (Boost_FOUND)
     target_include_directories(easy3d_${module} PRIVATE ${Boost_INCLUDE_DIRS})
diff --git a/tutorials/Tutorial_204_Viewer_Qt/main.cpp b/tutorials/Tutorial_204_Viewer_Qt/main.cpp
index a241c611..4c14a5a7 100644
--- a/tutorials/Tutorial_204_Viewer_Qt/main.cpp
+++ b/tutorials/Tutorial_204_Viewer_Qt/main.cpp
@@ -55,8 +55,8 @@ int main(int argc, char *argv[]) {
     QApplication::setAttribute(Qt::AA_UseDesktopOpenGL);
 
     QApplication::setAttribute(Qt::AA_ShareOpenGLContexts);
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 6, 0) && (QT_VERSION < QT_VERSION_CHECK(6, 0, 0)))
     QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
-#if (QT_VERSION >= QT_VERSION_CHECK(5, 6, 0))
     QApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
 #endif
 
diff --git a/tutorials/Tutorial_204_Viewer_Qt/window.cpp b/tutorials/Tutorial_204_Viewer_Qt/window.cpp
index eb02b940..bb9a6d0a 100644
--- a/tutorials/Tutorial_204_Viewer_Qt/window.cpp
+++ b/tutorials/Tutorial_204_Viewer_Qt/window.cpp
@@ -322,12 +322,14 @@ namespace easy3d {
 
     bool Window::okToContinue() {
         if (isWindowModified()) {
-            int r = QMessageBox::warning(this, tr("Viewer"),
-                                         tr("The model has been modified.\n"
-                                            "Do you want to save your changes?"),
-                                         QMessageBox::Yes | QMessageBox::Default,
-                                         QMessageBox::No,
-                                         QMessageBox::Cancel | QMessageBox::Escape);
+            QMessageBox::StandardButton r = QMessageBox::warning(
+                 this,
+                 tr("Viewer"),
+                 tr("The model has been modified.\n"
+                    "Do you want to save your changes?"),
+                 QMessageBox::Yes | QMessageBox::No | QMessageBox::Cancel,
+                 QMessageBox::Yes
+             );
             if (r == QMessageBox::Yes)
                 return onSave();
             else if (r == QMessageBox::Cancel)