diff --git a/cmake/jkqtplotter_common_qtsettings.cmake b/cmake/jkqtplotter_common_qtsettings.cmake
index e4b64f5714..e46832d562 100644
--- a/cmake/jkqtplotter_common_qtsettings.cmake
+++ b/cmake/jkqtplotter_common_qtsettings.cmake
@@ -6,3 +6,7 @@ set(CMAKE_AUTOUIC ON)
 
 find_package(QT NAMES Qt6 Qt5 COMPONENTS Core Gui Widgets PrintSupport Svg Xml OpenGL REQUIRED)
 find_package(Qt${QT_VERSION_MAJOR} COMPONENTS Core Gui Widgets PrintSupport Svg Xml OpenGL REQUIRED)
+if(${QT_VERSION_MAJOR}>=6)
+    find_package(Qt${QT_VERSION_MAJOR} COMPONENTS OpenGLWidgets REQUIRED)
+
+endif()
diff --git a/examples/jkqtmathtext_test/testform.cpp b/examples/jkqtmathtext_test/testform.cpp
index 3847eb0544..27fea445ec 100644
--- a/examples/jkqtmathtext_test/testform.cpp
+++ b/examples/jkqtmathtext_test/testform.cpp
@@ -400,7 +400,9 @@ void TestForm::updateMath()
 
     painter.begin(&pix);
     if (ui->chkAntiAlias->isChecked()) painter.setRenderHint(QPainter::Antialiasing);
+#if (QT_VERSION<QT_VERSION_CHECK(6, 0, 0))
     if (ui->chkAntiAliasHQ->isChecked()) painter.setRenderHint(QPainter::HighQualityAntialiasing);
+#endif
     if (ui->chkAntiAliasText->isChecked()) painter.setRenderHint(QPainter::TextAntialiasing);
     if (ui->chkSmoothTransform->isChecked()) painter.setRenderHint(QPainter::QPainter::SmoothPixmapTransform);
     ht.start();
diff --git a/lib/jkqtcommon/jkqtpbasicimagetools.cpp b/lib/jkqtcommon/jkqtpbasicimagetools.cpp
index 8277ae5f46..7fd08f1198 100644
--- a/lib/jkqtcommon/jkqtpbasicimagetools.cpp
+++ b/lib/jkqtcommon/jkqtpbasicimagetools.cpp
@@ -25,6 +25,12 @@
 #ifdef QT_XML_LIB
 #  include <QtXml/QtXml>
 #endif
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+#include<QRegularExpression>
+#include<QRegularExpressionMatch>
+#else
+#include<QRegExp>
+#endif
 
 const int JKQTPImageTools::PALETTE_ICON_WIDTH = 64;
 const int JKQTPImageTools::PALETTE_IMAGEICON_HEIGHT = 64;
@@ -2609,7 +2615,7 @@ JKQTPImageTools::LUTType JKQTPBuildColorPaletteLUTLinInterpolate(const QMap<doub
 {
     QList<QPair<double, QRgb> > itemsi;
     for (auto it=items.begin(); it!=items.end(); ++it) {
-        itemsi.append(qMakePair<double, QRgb>(it.key(), it.value()));
+        itemsi.append(QPair<double, QRgb>(it.key(), it.value()));
     }
     return JKQTPBuildColorPaletteLUTLinInterpolateSorted(itemsi, lut_size);
 }
@@ -2618,7 +2624,7 @@ JKQTPImageTools::LUTType JKQTPBuildColorPaletteLUT(const QMap<double, QRgb> &ite
 {
     QList<QPair<double, QRgb> > itemsi;
     for (auto it=items.begin(); it!=items.end(); ++it) {
-        itemsi.append(qMakePair<double, QRgb>(it.key(), it.value()));
+        itemsi.append(QPair<double, QRgb>(it.key(), it.value()));
     }
     return JKQTPBuildColorPaletteLUTSorted(itemsi, lut_size);
 }
@@ -2820,26 +2826,48 @@ QVector<int> JKQTPImageTools::registerPalettesFromFile(const QString &filename,
             bool has4=false;
             bool rgb255=false;
             QList<QPair<double, QRgb> > pal;
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+            QRegularExpression rx3("\\s*([0-9eE.+-]+)\\s*([,\\t ])\\s*([0-9eE.+-]+)\\s*\\2\\s*([0-9eE.+-]+)\\s*", QRegularExpression::CaseInsensitiveOption|QRegularExpression::InvertedGreedinessOption);
+            QRegularExpression rx4("\\s*([0-9eE.+-]+)\\s*([,\\t ])\\s*([0-9eE.+-]+)\\s*\\2\\s*([0-9eE.+-]+)\\s*\\2\\s*([0-9eE.+-]+)\\s*", QRegularExpression::CaseInsensitiveOption|QRegularExpression::InvertedGreedinessOption);
+#else
             QRegExp rx3("\\s*([0-9eE.+-]+)\\s*([,\\t ])\\s*([0-9eE.+-]+)\\s*\\2\\s*([0-9eE.+-]+)\\s*", Qt::CaseInsensitive);
             rx3.setMinimal(false);
             QRegExp rx4("\\s*([0-9eE.+-]+)\\s*([,\\t ])\\s*([0-9eE.+-]+)\\s*\\2\\s*([0-9eE.+-]+)\\s*\\2\\s*([0-9eE.+-]+)\\s*", Qt::CaseInsensitive);
             rx4.setMinimal(false);
+#endif
+
             // determine format
             for (int i=slt.size()-1; i>=0; i--) {
                 slt[i]=slt[i].trimmed();
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+                const auto m4=rx4.match(slt[i]);
+                const auto m3=rx3.match(slt[i]);
+                if (m4.hasMatch()) {
+                    const double r=JKQTPImagePlot_QStringToDouble(m4.captured(3));
+                    const double g=JKQTPImagePlot_QStringToDouble(m4.captured(4));
+                    const double b=JKQTPImagePlot_QStringToDouble(m4.captured(5));
+#else
                 if (rx4.indexIn(slt[i])>=0) {
+                    const double r=JKQTPImagePlot_QStringToDouble(rx4.cap(3));
+                    const double g=JKQTPImagePlot_QStringToDouble(rx4.cap(4));
+                    const double b=JKQTPImagePlot_QStringToDouble(rx4.cap(5));
+#endif
                     has4=true;
-                    double r=JKQTPImagePlot_QStringToDouble(rx4.cap(3));
-                    double g=JKQTPImagePlot_QStringToDouble(rx4.cap(4));
-                    double b=JKQTPImagePlot_QStringToDouble(rx4.cap(5));
                     if (r>1.0 || g>1.0 || b>1.0) {
                         rgb255=true;
                     }
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+                } else if (m3.hasMatch()) {
+                    const double r=JKQTPImagePlot_QStringToDouble(m3.captured(1));
+                    const double g=JKQTPImagePlot_QStringToDouble(m3.captured(3));
+                    const double b=JKQTPImagePlot_QStringToDouble(m3.captured(4));
+#else
                 } else if (rx3.indexIn(slt[i])>=0) {
-                    has4=false;
                     double r=JKQTPImagePlot_QStringToDouble(rx3.cap(1));
                     double g=JKQTPImagePlot_QStringToDouble(rx3.cap(3));
                     double b=JKQTPImagePlot_QStringToDouble(rx3.cap(4));
+#endif
+                    has4=false;
                     if (r>1.0 || g>1.0 || b>1.0) {
                         rgb255=true;
                     }
@@ -2852,6 +2880,20 @@ QVector<int> JKQTPImageTools::registerPalettesFromFile(const QString &filename,
             for (int i=0; i<slt.size(); i++) {
                 double x=0;
                 double r=0, g=0, b=0;
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+                const auto m4=rx4.match(slt[i]);
+                const auto m3=rx3.match(slt[i]);
+                if (has4 && m4.hasMatch()) {
+                    x=JKQTPImagePlot_QStringToDouble(m4.captured(1));
+                    r=JKQTPImagePlot_QStringToDouble(m4.captured(3));
+                    g=JKQTPImagePlot_QStringToDouble(m4.captured(4));
+                    b=JKQTPImagePlot_QStringToDouble(m4.captured(5));
+                } else if (!has4 && m3.hasMatch()) {
+                    x=i;
+                    r=JKQTPImagePlot_QStringToDouble(m3.captured(1));
+                    g=JKQTPImagePlot_QStringToDouble(m3.captured(3));
+                    b=JKQTPImagePlot_QStringToDouble(m3.captured(4));
+#else
                 if (has4 && rx4.indexIn(slt[i])>=0) {
                     x=JKQTPImagePlot_QStringToDouble(rx4.cap(1));
                     r=JKQTPImagePlot_QStringToDouble(rx4.cap(3));
@@ -2863,15 +2905,16 @@ QVector<int> JKQTPImageTools::registerPalettesFromFile(const QString &filename,
                     g=JKQTPImagePlot_QStringToDouble(rx3.cap(3));
                     b=JKQTPImagePlot_QStringToDouble(rx3.cap(4));
                     //qDebug()<<r<<g<<b;
+#endif
                 } else {
                     ok=false;
                     break;
                 }
                 if (ok) {
                     if (!rgb255) {
-                        pal<<qMakePair(x, qRgb(qBound(0,static_cast<int>(round(255*r)), 255), qBound(0,static_cast<int>(round(255*g)), 255), qBound(0,static_cast<int>(round(255*b)), 255)));
+                        pal<<QPair<double,QRgb>(x, qRgb(qBound(0,static_cast<int>(round(255*r)), 255), qBound(0,static_cast<int>(round(255*g)), 255), qBound(0,static_cast<int>(round(255*b)), 255)));
                     } else {
-                        pal<<qMakePair(x, qRgb(qBound(0,static_cast<int>(round(r)), 255), qBound(0,static_cast<int>(round(g)), 255), qBound(0,static_cast<int>(round(b)), 255)));
+                        pal<<QPair<double,QRgb>(x, qRgb(qBound(0,static_cast<int>(round(r)), 255), qBound(0,static_cast<int>(round(g)), 255), qBound(0,static_cast<int>(round(b)), 255)));
                     }
                 }
             }
diff --git a/lib/jkqtcommon/jkqtpstringtools.cpp b/lib/jkqtcommon/jkqtpstringtools.cpp
index 261ae2e0eb..55182e1d6a 100644
--- a/lib/jkqtcommon/jkqtpstringtools.cpp
+++ b/lib/jkqtcommon/jkqtpstringtools.cpp
@@ -45,7 +45,12 @@ Copyright (c) 2008-2020 Jan W. Krieger (<jan@jkrieger.de>)
 #include <ctype.h>
 #include <sstream>
 #include <locale>
-
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+#include<QRegularExpression>
+#include<QRegularExpressionMatch>
+#else
+#include<QRegExp>
+#endif
 
 std::string jkqtp_tolower(const std::string& s){
   std::string d;
@@ -527,6 +532,24 @@ QString jkqtp_QColor2String(QColor color, bool useSpecialTransparencySyntax) {
 
 QColor jkqtp_String2QColor(const QString &color)
 {
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+    QRegularExpression rxP("(.+)\\s*,\\s*(\\d+\\.?\\d+)\\%");
+    QRegularExpression rxNP("(.+)\\s*,\\s*([\\d]+)");
+    const auto mP=rxP.match(color);
+    if (mP.hasMatch()) {
+        QColor col(mP.captured(1));
+        double a=QLocale::c().toDouble(mP.captured(2));
+        col.setAlphaF(a/100.0);
+        return col;
+    }
+    const auto mNP=rxNP.match(color);
+    if (mNP.hasMatch()) {
+        QColor col(mNP.captured(1));
+        double a=QLocale::c().toInt(mNP.captured(2));
+        col.setAlphaF(a/255.0);
+        return col;
+    }
+#else
     QRegExp rxP("(.+)\\s*,\\s*(\\d+\\.?\\d+)\\%");
     QRegExp rxNP("(.+)\\s*,\\s*([\\d]+)");
     if (rxP.exactMatch(color)) {
@@ -541,6 +564,7 @@ QColor jkqtp_String2QColor(const QString &color)
         col.setAlphaF(a/255.0);
         return col;
     }
+#endif
     return QColor(color);
 }
 
diff --git a/lib/jkqtcommon/jkqttools.cpp b/lib/jkqtcommon/jkqttools.cpp
index 1c27c20f89..da3230e746 100644
--- a/lib/jkqtcommon/jkqttools.cpp
+++ b/lib/jkqtcommon/jkqttools.cpp
@@ -23,9 +23,14 @@
 
 #include <QList>
 #include <QApplication>
-#include <QDesktopWidget>
 #include <QLocale>
 #include <QtCore>
+#if (QT_VERSION>QT_VERSION_CHECK(5, 3, 0))
+#  include <QScreen>
+#  include <QGuiApplication>
+#else
+#  include <QDesktopWidget>
+#endif
 
 void jksaveWidgetGeometry(QSettings& settings, QWidget* widget, const QString& prefix) {
     settings.setValue(prefix+"pos", widget->pos());
@@ -34,11 +39,15 @@ void jksaveWidgetGeometry(QSettings& settings, QWidget* widget, const QString& p
 
 void jkloadWidgetGeometry(QSettings& settings, QWidget* widget, QPoint defaultPosition, QSize defaultSize, const QString& prefix) {
     QPoint pos = settings.value(prefix+"pos", defaultPosition).toPoint();
-    QSize size = settings.value(prefix+"size", defaultSize).toSize();
-
-    widget->resize(size.boundedTo(QApplication::desktop()->screenGeometry(widget).size()));
-    if (pos.x()<0 || pos.x()>QApplication::desktop()->screenGeometry(widget).width()) pos.setX(0);
-    if (pos.y()<0 || pos.y()>QApplication::desktop()->screenGeometry(widget).height()) pos.setY(0);
+    const QSize size = settings.value(prefix+"size", defaultSize).toSize();
+#if (QT_VERSION>=QT_VERSION_CHECK(5, 3, 0))
+    const auto widgeo = widget->screen()->geometry();
+#else
+    const auto widgeo = QApplication::desktop()->screenGeometry(widget);
+#endif
+    widget->resize(size.boundedTo(widgeo.size()));
+    if (pos.x()<0 || pos.x()>widgeo.width()) pos.setX(0);
+    if (pos.y()<0 || pos.y()>widgeo.height()) pos.setY(0);
     widget->move(pos);
 }
 
@@ -78,21 +87,39 @@ QString jkVariantListToString(const QList<QVariant>& data, const QString& separa
     for (int i=0; i<data.size(); i++) {
         if (i>0) r=r+separator;
         QVariant v=data[i];
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+        if (v.typeId()==QMetaType::Bool) r=r+loc.toString(v.toBool());
+        else if (v.typeId()==QMetaType::Char) r=r+loc.toString(v.toInt());
+        else if (v.typeId()==QMetaType::QDate) r=r+loc.toString(v.toDate());
+        else if (v.typeId()==QMetaType::QDateTime) r=r+loc.toString(v.toDateTime());
+        else if (v.typeId()==QMetaType::Double) r=r+loc.toString(v.toDouble());
+        else if (v.typeId()==QMetaType::Int) r=r+loc.toString(v.toInt());
+        else if (v.typeId()==QMetaType::LongLong) r=r+loc.toString(v.toLongLong());
+        else if (v.typeId()==QMetaType::QString) r=r+QString("\"%1\"").arg(v.toString().replace("\"", "_").replace("\t", " ").replace("\r", "").replace("\n", " ").replace(",", " ").replace(";", " "));
+        else if (v.typeId()==QMetaType::QTime) r=r+loc.toString(v.toTime());
+        else if (v.typeId()==QMetaType::UInt) r=r+loc.toString(v.toUInt());
+        else if (v.typeId()==QMetaType::ULongLong) r=r+loc.toString(v.toULongLong());
+        else r=r+v.toString();
+
+#else
+#  define QVARIANT_TYPESBASE QVariant
         switch (v.type()) {
-            case QVariant::Bool: r=r+loc.toString(v.toBool()); break;
-            case QVariant::Char: r=r+loc.toString(v.toInt()); break;
-            case QVariant::Date: r=r+loc.toString(v.toDate()); break;
-            case QVariant::DateTime: r=r+loc.toString(v.toDateTime()); break;
-            case QVariant::Double: r=r+loc.toString(v.toDouble()); break;
-            case QVariant::Int: r=r+loc.toString(v.toInt()); break;
-            case QVariant::LongLong: r=r+loc.toString(v.toLongLong()); break;
-            case QVariant::String: r=r+QString("\"%1\"").arg(v.toString().replace("\"", "_").replace("\t", " ").replace("\r", "").replace("\n", " ").replace(",", " ").replace(";", " ")); break;
-            case QVariant::Time: r=r+loc.toString(v.toTime()); break;
-            case QVariant::UInt: r=r+loc.toString(v.toUInt()); break;
-            case QVariant::ULongLong: r=r+loc.toString(v.toULongLong()); break;
+
+            case QVARIANT_TYPESBASE::Bool: r=r+loc.toString(v.toBool()); break;
+            case QVARIANT_TYPESBASE::Char: r=r+loc.toString(v.toInt()); break;
+            case QVARIANT_TYPESBASE::Date: r=r+loc.toString(v.toDate()); break;
+            case QVARIANT_TYPESBASE::DateTime: r=r+loc.toString(v.toDateTime()); break;
+            case QVARIANT_TYPESBASE::Double: r=r+loc.toString(v.toDouble()); break;
+            case QVARIANT_TYPESBASE::Int: r=r+loc.toString(v.toInt()); break;
+            case QVARIANT_TYPESBASE::LongLong: r=r+loc.toString(v.toLongLong()); break;
+            case QVARIANT_TYPESBASE::String: r=r+QString("\"%1\"").arg(v.toString().replace("\"", "_").replace("\t", " ").replace("\r", "").replace("\n", " ").replace(",", " ").replace(";", " ")); break;
+            case QVARIANT_TYPESBASE::Time: r=r+loc.toString(v.toTime()); break;
+            case QVARIANT_TYPESBASE::UInt: r=r+loc.toString(v.toUInt()); break;
+            case QVARIANT_TYPESBASE::ULongLong: r=r+loc.toString(v.toULongLong()); break;
             //case : r=r+loc.toString(v.); break;
             default: r=r+v.toString(); break;
         }
+#endif
     }
     return r;
 }
@@ -101,7 +128,11 @@ JKQTCOMMON_LIB_EXPORT QString jkqtp_filenameize(const QString& data) {
     QString r;
     QString data1=data.simplified();
     for (int i=0; i<data1.size(); i++) {
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+        const auto c=data1[i];
+#else
         QCharRef c=data1[i];
+#endif
         if (c.isLetterOrNumber() || (c=='-') || (c=='_') || (c=='.')) {
             r+=c;
         } else {
@@ -167,7 +198,11 @@ QString jkqtp_MouseButton2String(Qt::MouseButton button, bool useNONE)
     }
     if (button==Qt::LeftButton) return "LEFT";
     if (button==Qt::RightButton) return "RIGHT";
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+    if (button==Qt::MiddleButton) return "MIDDLE";
+#else
     if (button==Qt::MidButton) return "MIDDLE";
+#endif
     if (button==Qt::BackButton) return "BACK";
     if (button==Qt::ForwardButton) return "FORWARD";
     if (button==Qt::TaskButton) return "TASK";
@@ -200,7 +235,11 @@ Qt::MouseButton jkqtp_String2MouseButton(const QString &button)
     auto but=button.toUpper().trimmed();
     if (but=="LEFT") return Qt::LeftButton;
     if (but=="RIGHT") return Qt::RightButton;
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+    if (but=="MIDDLE") return Qt::MiddleButton;
+#else
     if (but=="MIDDLE") return Qt::MidButton;
+#endif
     if (but=="BACK") return Qt::BackButton;
     if (but=="FORWARD") return Qt::ForwardButton;
     if (but=="TASK") return Qt::TaskButton;
diff --git a/lib/jkqtfastplotter/CMakeLists.txt b/lib/jkqtfastplotter/CMakeLists.txt
index 55c9a82599..39fb3a8201 100644
--- a/lib/jkqtfastplotter/CMakeLists.txt
+++ b/lib/jkqtfastplotter/CMakeLists.txt
@@ -79,7 +79,10 @@ if(JKQtPlotter_BUILD_STATIC_LIBS)
     endif()
     target_compile_features(${lib_name} PUBLIC cxx_std_11)
     target_link_libraries(${lib_name} PUBLIC Qt${QT_VERSION_MAJOR}::Core Qt${QT_VERSION_MAJOR}::Gui Qt${QT_VERSION_MAJOR}::Widgets Qt${QT_VERSION_MAJOR}::PrintSupport Qt${QT_VERSION_MAJOR}::OpenGL JKQTCommonLib)
-  	target_include_directories(${lib_name} PUBLIC
+    if(${QT_VERSION_MAJOR}>=6)
+        target_link_libraries(${lib_name} PUBLIC t${QT_VERSION_MAJOR}::OpenGLWidgets)
+    endif()
+    target_include_directories(${lib_name} PUBLIC
         $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/../>
         $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>  
     )
diff --git a/lib/jkqtfastplotter/jkqtfastplotter.cpp b/lib/jkqtfastplotter/jkqtfastplotter.cpp
index bdf8f2ae41..fbf1f13149 100644
--- a/lib/jkqtfastplotter/jkqtfastplotter.cpp
+++ b/lib/jkqtfastplotter/jkqtfastplotter.cpp
@@ -69,7 +69,11 @@ void JKQTFPPlot::paint(QPainter& painter) {
 }
 
 JKQTFastPlotter::JKQTFastPlotter(QWidget *parent) :
-    QGLWidget(QGLFormat(QGL::StencilBuffer | QGL::AlphaChannel | QGL::Rgba), parent)//, mutexRepaint(QMutex::Recursive), mutexRepaintData(QMutex::Recursive), mutexRepaintSystem(QMutex::Recursive)
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+    JKQTFASTPLOTTER_BASE(parent)
+#else
+    JKQTFASTPLOTTER_BASE(QGLFormat(QGL::StencilBuffer | QGL::AlphaChannel | QGL::Rgba), parent)//, mutexRepaint(QMutex::Recursive), mutexRepaintData(QMutex::Recursive), mutexRepaintSystem(QMutex::Recursive)
+#endif
 {
     mouseDragStart=QPoint(0,0);
     mouseDragEnd=QPoint(0,0);
@@ -263,7 +267,7 @@ void JKQTFastPlotter::mouseReleaseEvent(QMouseEvent *event)
 }
 
 void JKQTFastPlotter::resizeEvent(QResizeEvent *event) {
-     QGLWidget::resizeEvent(event);
+     JKQTFASTPLOTTER_BASE::resizeEvent(event);
      if (width() > image.width() || height() > image.height()) {
          QImage newImage(QSize(width(), height()), QImage::Format_ARGB32);
          image=newImage;
@@ -350,7 +354,7 @@ void JKQTFastPlotter::plotSystem(QPainter& painter) {
             systemPath.moveTo(x2p(x), internalPlotBorderTop+plotHeight+tickLength);
             systemPath.lineTo(x2p(x), internalPlotBorderTop+plotHeight-tickLength);
             QString text=QLocale::system().toString(x);
-            painter.drawText(QPointF(x2p(x)-fmTicks.width(text)/2.0, internalPlotBorderTop+plotHeight+fmTicks.ascent()+fmTicks.width("x")/2.0+tickLength), text);
+            painter.drawText(QPointF(x2p(x)-fmTicks.boundingRect(text).width()/2.0, internalPlotBorderTop+plotHeight+fmTicks.ascent()+fmTicks.boundingRect("x").width()/2.0+tickLength), text);
         }
         if (xAxisLog) {
             x=x*10.0;
@@ -368,7 +372,7 @@ void JKQTFastPlotter::plotSystem(QPainter& painter) {
             systemPath.moveTo(x2p(x), internalPlotBorderTop+plotHeight+tickLength);
             systemPath.lineTo(x2p(x), internalPlotBorderTop+plotHeight-tickLength);
             QString text=QLocale::system().toString(x);
-            painter.drawText(QPointF(x2p(x)-fmTicks.width(text)/2.0, internalPlotBorderTop+plotHeight+fmTicks.ascent()+fmTicks.width("x")/2.0+tickLength), text);
+            painter.drawText(QPointF(x2p(x)-fmTicks.boundingRect(text).width()/2.0, internalPlotBorderTop+plotHeight+fmTicks.ascent()+fmTicks.boundingRect("x").width()/2.0+tickLength), text);
         }
         if (xAxisLog) {
             x=x/10.0;
@@ -387,7 +391,7 @@ void JKQTFastPlotter::plotSystem(QPainter& painter) {
             systemPath.moveTo(internalPlotBorderLeft-tickLength, y2p(y));
             systemPath.lineTo(internalPlotBorderLeft+tickLength, y2p(y));
             QString text=QLocale::system().toString(y);
-            painter.drawText(QPointF(internalPlotBorderLeft-fmTicks.width("x")/2.0-fmTicks.width(text)-tickLength, y2p(y)+fmTicks.ascent()/2.0), text);
+            painter.drawText(QPointF(internalPlotBorderLeft-fmTicks.boundingRect("x").width()/2.0-fmTicks.boundingRect(text).width()-tickLength, y2p(y)+fmTicks.ascent()/2.0), text);
         }
         if (yAxisLog) {
             y=y*10.0;
@@ -405,7 +409,7 @@ void JKQTFastPlotter::plotSystem(QPainter& painter) {
             systemPath.moveTo(internalPlotBorderLeft-tickLength, y2p(y));
             systemPath.lineTo(internalPlotBorderLeft+tickLength, y2p(y));
             QString text=QLocale::system().toString(y);
-            painter.drawText(QPointF(internalPlotBorderLeft-fmTicks.width("x")/2.0-fmTicks.width(text)-tickLength, y2p(y)+fmTicks.ascent()/2.0), text);
+            painter.drawText(QPointF(internalPlotBorderLeft-fmTicks.boundingRect("x").width()/2.0-fmTicks.boundingRect(text).width()-tickLength, y2p(y)+fmTicks.ascent()/2.0), text);
         }
         if (yAxisLog) {
             y=y/10.0;
@@ -453,11 +457,11 @@ void JKQTFastPlotter::plotSystem(QPainter& painter) {
     if (xAxisLabelVisible) {
         painter.setPen(pSystem);
         painter.setFont(fLabels);
-        painter.drawText(QPointF(internalPlotBorderLeft+plotWidth-fmLabels.width(xAxisLabel), internalPlotBorderTop+plotHeight+fmTicks.height()+fmTicks.width("x")/2.0+fmLabels.ascent()+tickLength), xAxisLabel);
+        painter.drawText(QPointF(internalPlotBorderLeft+plotWidth-fmLabels.boundingRect(xAxisLabel).width(), internalPlotBorderTop+plotHeight+fmTicks.height()+fmTicks.boundingRect("x").width()/2.0+fmLabels.ascent()+tickLength), xAxisLabel);
     }
     if (yAxisLabelVisible) {
         painter.save(); auto __finalpaintinner=JKQTPFinally([&painter]() {painter.restore();});
-        painter.translate(fmLabels.ascent(), internalPlotBorderTop+fmLabels.width(yAxisLabel));
+        painter.translate(fmLabels.ascent(), internalPlotBorderTop+fmLabels.boundingRect(yAxisLabel).width());
         painter.rotate(-90);
         painter.drawText(QPointF(0, 0), yAxisLabel);
 
diff --git a/lib/jkqtfastplotter/jkqtfastplotter.h b/lib/jkqtfastplotter/jkqtfastplotter.h
index d9f8e74a2e..ff928dba42 100644
--- a/lib/jkqtfastplotter/jkqtfastplotter.h
+++ b/lib/jkqtfastplotter/jkqtfastplotter.h
@@ -34,7 +34,13 @@
 #include <cmath>
 #include <iostream>
 #include <QMutex>
+#if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+#include <QtOpenGLWidgets/QOpenGLWidget>
+#define JKQTFASTPLOTTER_BASE QOpenGLWidget
+#else
 #include <QGLWidget>
+#define JKQTFASTPLOTTER_BASE QGLWidget
+#endif
 #include "jkqtcommon/jkqtpmathtools.h"
 #ifdef DEBUG_TIMING
 #  include "jkqtcommon/jkqtphighrestimer.h"
@@ -83,7 +89,13 @@ class JKQTFPPlot;
     .
 
 */
-class JKQTFASTPLOTTER_LIB_EXPORT JKQTFastPlotter : public QGLWidget {
+class JKQTFASTPLOTTER_LIB_EXPORT JKQTFastPlotter :
+        #if (QT_VERSION>=QT_VERSION_CHECK(6, 0, 0))
+        public QOpenGLWidget
+        #else
+        public QGLWidget
+        #endif
+{
         Q_OBJECT
     public:
 
diff --git a/lib/jkqtmathtext/jkqtmathtext.cpp b/lib/jkqtmathtext/jkqtmathtext.cpp
index 55cf3f3a18..9d235d4d48 100644
--- a/lib/jkqtmathtext/jkqtmathtext.cpp
+++ b/lib/jkqtmathtext/jkqtmathtext.cpp
@@ -30,6 +30,7 @@
 #include <QApplication>
 #include <QPainterPath>
 
+
 const double JKQTMathText::ABS_MIN_LINEWIDTH=0.02;
 
 QPainterPath makeHBracePath(double x, double ybrace, double width, double bw, double cubicshrink=0.5, double cubiccontrolfac=0.3) {
@@ -277,14 +278,14 @@ void JKQTMathText::MTtextNode::getSizeInternal(QPainter& painter, JKQTMathText::
     QRectF tbr=parent->getTightBoundingRect(f, txt, painter.device()); //fm.tightBoundingRect(txt);
     if (txt=="|") {
         br=fm.boundingRect("X");
-        tbr=QRectF(0,0,fm.width("X"), fm.ascent());//fm.boundingRect("X");
+        tbr=QRectF(0,0,fm.boundingRect("X").width(), fm.ascent());//fm.boundingRect("X");
         br.setWidth(0.7*br.width());
     }
     width=br.width();//width(text);
 
     if (txt.size()>0) {
         if (txt[0].isSpace() /*&& br.width()<=0*/) width=width+fm.boundingRect("I").width();
-        if (txt.size()>1 && txt[txt.size()-1].isSpace() /*&& (fm.boundingRect("a ").width()==fm.boundingRect("a").width())*/) width=width+fm.width("I");
+        if (txt.size()>1 && txt[txt.size()-1].isSpace() /*&& (fm.boundingRect("a ").width()==fm.boundingRect("a").width())*/) width=width+fm.boundingRect("I").width();
     }
 
     //qDebug()<<"text: "<<text<<"   "<<tbr.height()<<tbr.top()<<tbr.bottom();
@@ -340,7 +341,7 @@ double JKQTMathText::MTtextNode::draw(QPainter& painter, double x, double y, JKQ
     QFontMetricsF fm(f, painter.device());
     /*if (txt.size()>1 && txt[txt.size()-1].isSpace()) {
         QFontMetricsF fm(f, painter.device());
-        //if ((fm.width("a ")==fm.width("a"))) dx=fm.boundingRect("I").width();
+        //if ((fm.QFMF_WIDTH("a ")==fm.QFMF_WIDTH("a"))) dx=fm.boundingRect("I").QFMF_WIDTH();
     }*/
 
     if (!hasDigits || !f.italic()) {
@@ -367,7 +368,7 @@ double JKQTMathText::MTtextNode::draw(QPainter& painter, double x, double y, JKQ
                     painter.setFont(ff);
                     painter.drawText(QPointF(xx, y), QString(txt[i]));
                 }
-                xx=xx+fmff.width(txt[i]);
+                xx=xx+fmff.boundingRect(txt[i]).width();
             } else {
                 if (currentEv.font==MTEblackboard && parent->blackboardSimulated) {
                     QPainterPath path;
@@ -377,7 +378,7 @@ double JKQTMathText::MTtextNode::draw(QPainter& painter, double x, double y, JKQ
                     painter.setFont(f);
                     painter.drawText(QPointF(xx, y), QString(txt[i]));
                 }
-                xx=xx+fm.width(txt[i]);
+                xx=xx+fm.boundingRect(txt[i]).width();
             }
             i++;
         }
@@ -465,7 +466,7 @@ void JKQTMathText::MTinstruction1Node::getSizeInternal(QPainter& painter, JKQTMa
     child->getSize(painter, ev, width, baselineHeight, overallHeight, strikeoutPos);
     if (name=="colorbox" || name=="fbox" || name=="boxed") {
         QFontMetricsF fm(ev.getFont(parent));
-        double xw=fm.width("x");
+        double xw=fm.boundingRect("x").width();
         width+=xw;
         overallHeight+=xw;
         baselineHeight+=xw/2.0;
@@ -488,7 +489,7 @@ double JKQTMathText::MTinstruction1Node::draw(QPainter& painter, double x, doubl
         child->getSize(painter, currentEv, width, baselineHeight, overallHeight, strikeoutPos);
         QPen p=painter.pen();
         QFontMetricsF fm(currentEv.getFont(parent));
-        double xw=fm.width("x");
+        double xw=fm.boundingRect("x").width();
         p.setColor(fcol);
         painter.setPen(p);
         painter.drawRect(QRectF(x,y-baselineHeight-xw/2,width+xw,overallHeight+xw));
@@ -2860,11 +2861,11 @@ void JKQTMathText::MTsymbolNode::getSizeInternal(QPainter& painter, JKQTMathText
     if (currentEv.insideMath) width=qMax(parent->getTightBoundingRect(f, symb, painter.device()).width(),parent->getTightBoundingRect(f, "i", painter.device()).width());//fm.width(symbol);
     else width=fm.boundingRect(symb).width();//fm.width(symbol);
 
-    width=qMax(fm.width("j"), width);
+    width=qMax(fm.boundingRect("j").width(), width);
     if (symb.isEmpty()) {
-        width=fm.width("a");
-        if (symbolName=="|") width=fm.width("1")*0.8;
-        else if (symbolName=="infty") width=fm.width("M");
+        width=fm.boundingRect("a").width();
+        if (symbolName=="|") width=fm.boundingRect("1").width()*0.8;
+        else if (symbolName=="infty") width=fm.boundingRect("M").width();
         else if (symbolName=="quad" || symbolName=="qquad") width=parent->getTightBoundingRect(f, "M", painter.device()).width();
         else if (symbolName==" " || symbolName=="space") width=parent->getTightBoundingRect(f, "x", painter.device()).width();
         else if (symbolName==";") width=parent->getTightBoundingRect(f, "x", painter.device()).width()*0.75;
@@ -2933,7 +2934,7 @@ double JKQTMathText::MTsymbolNode::draw(QPainter& painter, double x, double y, J
     p.setWidthF(fm.lineWidth());
     p.setStyle(Qt::SolidLine);
     painter.setPen(p);
-    double xwi=fm.width("x");
+    double xwi=fm.boundingRect("x").width();
     if (!props.symbol.isEmpty()) {
         // if the symbol has been recognized in the constructor: draw the symbol
         painter.drawText(QPointF(x+shift, y+props.yfactor*overallHeight), props.symbol);
@@ -2949,7 +2950,7 @@ double JKQTMathText::MTsymbolNode::draw(QPainter& painter, double x, double y, J
         f1.setItalic(false);
         painter.setFont(f1);
         painter.save(); auto __finalpaint=JKQTPFinally([&painter]() {painter.restore();});
-        painter.translate(x+shift+fm1.width("8")/3.0, y-fm1.xHeight());
+        painter.translate(x+shift+fm1.boundingRect("8").width()/3.0, y-fm1.xHeight());
         painter.rotate(90);
         painter.drawText(QPointF(0,0), "8");
 
@@ -2961,7 +2962,7 @@ double JKQTMathText::MTsymbolNode::draw(QPainter& painter, double x, double y, J
         painter.save(); auto __finalpaint=JKQTPFinally([&painter]() {painter.restore();});
         painter.translate(x+shift, y);
         painter.drawText(QPointF(0,0), "|");
-        painter.translate(fm1.width("8")/3.0, 0);
+        painter.translate(fm1.boundingRect("8").width()/3.0, 0);
         painter.drawText(QPointF(0,0), "|");
 
 
@@ -4876,7 +4877,9 @@ void JKQTMathTextLabel::internalPaint()
             //qDebug()<<"internalPaint(): "<<p.begin(&buffer);
             p.begin(&buffer);
             p.setRenderHint(QPainter::Antialiasing);
+#if (QT_VERSION<QT_VERSION_CHECK(6, 0, 0))
             p.setRenderHint(QPainter::HighQualityAntialiasing);
+#endif
             p.setRenderHint(QPainter::TextAntialiasing);
             size=m_mathText->getSize(p);
             p.end();
@@ -4889,7 +4892,9 @@ void JKQTMathTextLabel::internalPaint()
             //qDebug()<<"internalPaint(): "<<p.begin(&buffer);
             p.begin(&buffer);
             p.setRenderHint(QPainter::Antialiasing);
+#if (QT_VERSION<QT_VERSION_CHECK(6, 0, 0))
             p.setRenderHint(QPainter::HighQualityAntialiasing);
+#endif
             p.setRenderHint(QPainter::TextAntialiasing);
             m_mathText->draw(p,alignment(), QRectF(QPointF(0,0), size));
             p.end();
diff --git a/lib/jkqtplotter/jkqtpbaseplotter.cpp b/lib/jkqtplotter/jkqtpbaseplotter.cpp
index b99b4ac40a..0663212d4e 100644
--- a/lib/jkqtplotter/jkqtpbaseplotter.cpp
+++ b/lib/jkqtplotter/jkqtpbaseplotter.cpp
@@ -3753,11 +3753,13 @@ void JKQTBasePlotter::saveAsPixelImage(const QString& filename, bool displayPrev
             png.fill(Qt::transparent);
             JKQTPEnhancedPainter painter;
             painter.begin(&png);
-            painter.setRenderHint(JKQTPEnhancedPainter::NonCosmeticDefaultPen, true);
             painter.setRenderHint(JKQTPEnhancedPainter::Antialiasing);
             painter.setRenderHint(JKQTPEnhancedPainter::TextAntialiasing);
             painter.setRenderHint(JKQTPEnhancedPainter::SmoothPixmapTransform);
+#if (QT_VERSION<QT_VERSION_CHECK(6, 0, 0))
+            painter.setRenderHint(JKQTPEnhancedPainter::NonCosmeticDefaultPen, true);
             painter.setRenderHint(JKQTPEnhancedPainter::HighQualityAntialiasing);
+#endif
 
             /*calcPlotScaling(painter);
             gridPaint(painter, png.rect().size());*/\
@@ -3809,11 +3811,13 @@ void JKQTBasePlotter::copyPixelImage() {
                 png.fill(Qt::transparent);
                 JKQTPEnhancedPainter painter;
                 painter.begin(&png);
-                painter.setRenderHint(JKQTPEnhancedPainter::NonCosmeticDefaultPen, true);
                 painter.setRenderHint(JKQTPEnhancedPainter::Antialiasing);
                 painter.setRenderHint(JKQTPEnhancedPainter::TextAntialiasing);
                 painter.setRenderHint(JKQTPEnhancedPainter::SmoothPixmapTransform);
+#if (QT_VERSION<QT_VERSION_CHECK(6, 0, 0))
+                painter.setRenderHint(JKQTPEnhancedPainter::NonCosmeticDefaultPen, true);
                 painter.setRenderHint(JKQTPEnhancedPainter::HighQualityAntialiasing);
+#endif
 
                 /*calcPlotScaling(painter);
                 gridPaint(painter, png.rect().size());*/
diff --git a/lib/jkqtplotter/jkqtpgraphsbase.cpp b/lib/jkqtplotter/jkqtpgraphsbase.cpp
index 4a1c3d8f49..83840bd62e 100644
--- a/lib/jkqtplotter/jkqtpgraphsbase.cpp
+++ b/lib/jkqtplotter/jkqtpgraphsbase.cpp
@@ -59,7 +59,9 @@ QImage JKQTPPlotElement::generateKeyMarker(QSize size)
         painter.setRenderHint(QPainter::Antialiasing, true);
         painter.setRenderHint(QPainter::TextAntialiasing, true);
         painter.setRenderHint(QPainter::SmoothPixmapTransform, true);
+#if (QT_VERSION<QT_VERSION_CHECK(6, 0, 0))
         painter.setRenderHint(QPainter::HighQualityAntialiasing, true);
+#endif
         QRectF rect(0,0,size.width(),size.height());
         drawKeyMarker(painter, rect);
     }
@@ -414,6 +416,7 @@ void JKQTPXYGraph::setXYColumns(int xCol, int yCol)
     setYColumn(yCol);
 }
 
+#if QT_VERSION<QT_VERSION_CHECK(6,0,0)
 void JKQTPXYGraph::setXYColumns(std::pair<int, int> xyColPair)
 {
     setXColumn(xyColPair.first);
@@ -425,6 +428,7 @@ void JKQTPXYGraph::setXYColumns(std::pair<size_t, size_t> xyColPair)
     setXColumn(xyColPair.first);
     setYColumn(xyColPair.second);
 }
+#endif
 
 void JKQTPXYGraph::setXYColumns(QPair<int, int> xyColPair)
 {
diff --git a/lib/jkqtplotter/jkqtpgraphsbase.h b/lib/jkqtplotter/jkqtpgraphsbase.h
index 856a98f05d..f5560b6516 100644
--- a/lib/jkqtplotter/jkqtpgraphsbase.h
+++ b/lib/jkqtplotter/jkqtpgraphsbase.h
@@ -605,10 +605,12 @@ public slots:
     void setXYColumns(size_t xCol, size_t yCol);
     /** \brief sets xColumn and yColumn at the same time */
     void setXYColumns(int xCol, int yCol);
+#if QT_VERSION<QT_VERSION_CHECK(6,0,0)
     /** \brief sets xColumn and yColumn at the same time */
     void setXYColumns(std::pair<int,int> xyColPair);
     /** \brief sets xColumn and yColumn at the same time */
     void setXYColumns(std::pair<size_t,size_t> xyColPair);
+#endif
     /** \brief sets xColumn and yColumn at the same time */
     void setXYColumns(QPair<int,int> xyColPair);
     /** \brief sets xColumn and yColumn at the same time */