diff --git a/src/core/iconfig.h b/src/core/iconfig.h
index d10701fa0c..d7dad076e4 100644
--- a/src/core/iconfig.h
+++ b/src/core/iconfig.h
@@ -6,6 +6,7 @@
 #include <QJsonArray>
 #include <QBitArray>
 #include <QDataStream>
+#include <QIODevice>
 
 namespace vnotex
 {
diff --git a/src/core/notebook/node.cpp b/src/core/notebook/node.cpp
index 9f8686e821..06de7f1ab4 100644
--- a/src/core/notebook/node.cpp
+++ b/src/core/notebook/node.cpp
@@ -8,6 +8,7 @@
 #include <core/exception.h>
 #include "notebook.h"
 #include "nodeparameters.h"
+#include <QRandomGenerator>
 
 using namespace vnotex;
 
@@ -483,7 +484,7 @@ QList<QSharedPointer<File>> Node::collectFiles()
 
 ID Node::generateSignature()
 {
-    return static_cast<ID>(QDateTime::currentDateTime().toSecsSinceEpoch() + (static_cast<qulonglong>(qrand()) << 32));
+    return static_cast<ID>(QDateTime::currentDateTime().toSecsSinceEpoch() + (static_cast<qulonglong>(QRandomGenerator::global()->generate()) << 32));
 }
 
 void Node::checkSignature()
diff --git a/src/core/notebook/notebookdatabaseaccess.cpp b/src/core/notebook/notebookdatabaseaccess.cpp
index a6bac152d5..610bb066f1 100644
--- a/src/core/notebook/notebookdatabaseaccess.cpp
+++ b/src/core/notebook/notebookdatabaseaccess.cpp
@@ -560,7 +560,12 @@ bool NotebookDatabaseAccess::updateNodeTags(Node *p_node)
     const auto &nodeTags = p_node->getTags();
 
     {
-        const auto tags = QSet<QString>::fromList(queryNodeTags(p_node->getId()));
+        QStringList list = queryNodeTags(p_node->getId());
+        QSet<QString> tags;
+        for (auto &s : list)
+        {
+            tags.insert(s);
+        }
         if (tags.isEmpty() && nodeTags.isEmpty()) {
             return true;
         }
@@ -691,7 +696,7 @@ QList<ID> NotebookDatabaseAccess::queryTagNodesRecursive(const QString &p_tag)
         }
     }
 
-    return allIds.toList();
+    return allIds.values();
 }
 
 QStringList NotebookDatabaseAccess::queryTagAndChildren(const QString &p_tag)
@@ -742,7 +747,7 @@ QStringList NotebookDatabaseAccess::getNodesOfTags(const QStringList &p_tags)
                 allIds.insert(id);
             }
         }
-        nodeIds = allIds.toList();
+        nodeIds = allIds.values();
     }
 
     for (const auto &id : nodeIds) {
diff --git a/src/core/notebookconfigmgr/vxnotebookconfigmgr.cpp b/src/core/notebookconfigmgr/vxnotebookconfigmgr.cpp
index 9551a6b2d1..bf13d1c879 100644
--- a/src/core/notebookconfigmgr/vxnotebookconfigmgr.cpp
+++ b/src/core/notebookconfigmgr/vxnotebookconfigmgr.cpp
@@ -465,7 +465,7 @@ QSharedPointer<Node> VXNotebookConfigMgr::loadNodeByPath(const QSharedPointer<No
         return p_root;
     }
 
-    auto paths = p.split('/', QString::SkipEmptyParts);
+    auto paths = p.split('/', Qt::SkipEmptyParts);
     auto node = p_root;
     for (auto &pa : paths) {
         // Find child @pa in @node.
diff --git a/src/export/webviewexporter.cpp b/src/export/webviewexporter.cpp
index 486f2bc229..69291a3ee8 100644
--- a/src/export/webviewexporter.cpp
+++ b/src/export/webviewexporter.cpp
@@ -19,6 +19,7 @@
 #include <utils/processutils.h>
 #include <utils/htmlutils.h>
 #include <core/file.h>
+#include <QRegExp>
 
 using namespace vnotex;
 
@@ -362,7 +363,7 @@ bool WebViewExporter::embedStyleResources(QString &p_html) const
 
     int pos = 0;
     while (pos < p_html.size()) {
-        int idx = p_html.indexOf(reg, pos);
+        int idx = reg.indexIn(p_html, pos);
         if (idx == -1) {
             break;
         }
@@ -393,7 +394,7 @@ bool WebViewExporter::embedBodyResources(const QUrl &p_baseUrl, QString &p_html)
 
     int pos = 0;
     while (pos < p_html.size()) {
-        int idx = p_html.indexOf(reg, pos);
+        int idx = reg.indexIn(p_html, pos);
         if (idx == -1) {
             break;
         }
@@ -440,7 +441,7 @@ bool WebViewExporter::fixBodyResources(const QUrl &p_baseUrl,
 
     int pos = 0;
     while (pos < p_html.size()) {
-        int idx = p_html.indexOf(reg, pos);
+        int idx = reg.indexIn(p_html, pos);
         if (idx == -1) {
             break;
         }
diff --git a/src/main.cpp b/src/main.cpp
index a28607cf96..4363903455 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -31,7 +31,6 @@ using namespace vnotex;
 
 void loadTranslators(QApplication &p_app);
 
-void initWebEngineSettings();
 
 void showMessageOnCommandLineIfAvailable(const QString &p_msg);
 
@@ -79,7 +78,6 @@ int main(int argc, char *argv[])
 
     Application app(argc, argv);
 
-    initWebEngineSettings();
 
     QAccessible::installFactory(&FakeAccessible::accessibleFactory);
 
@@ -253,12 +251,6 @@ void loadTranslators(QApplication &p_app)
     }
 }
 
-void initWebEngineSettings()
-{
-    auto settings = QWebEngineSettings::defaultSettings();
-    settings->setAttribute(QWebEngineSettings::LocalContentCanAccessRemoteUrls, true);
-}
-
 void showMessageOnCommandLineIfAvailable(const QString &p_msg)
 {
 #if defined(Q_OS_WIN)
diff --git a/src/src.pro b/src/src.pro
index 14595123cf..e3e1dd1f9c 100644
--- a/src/src.pro
+++ b/src/src.pro
@@ -2,7 +2,7 @@ lessThan(QT_MAJOR_VERSION, 5): error("requires Qt 5 and above")
 
 equals(QT_MAJOR_VERSION, 5):lessThan(QT_MINOR_VERSION, 12): error("requires Qt 5.12 and above")
 
-QT += core gui widgets webenginewidgets webchannel network svg printsupport
+QT += core gui widgets webenginewidgets webchannel network svg printsupport core5compat
 QT += sql
 
 CONFIG -= qtquickcompiler
diff --git a/src/unitedentry/iunitedentry.cpp b/src/unitedentry/iunitedentry.cpp
index b97e6ef335..7abbad8131 100644
--- a/src/unitedentry/iunitedentry.cpp
+++ b/src/unitedentry/iunitedentry.cpp
@@ -41,19 +41,19 @@ void IUnitedEntry::process(const QString &p_args,
         initOnFirstProcess();
     }
 
-    m_askedToStop.store(0);
+    m_askedToStop.storeRelaxed(0);
 
     return processInternal(p_args, p_popupWidgetFunc);
 }
 
 void IUnitedEntry::stop()
 {
-    m_askedToStop.store(1);
+    m_askedToStop.storeRelaxed(1);
 }
 
 bool IUnitedEntry::isAskedToStop() const
 {
-    return m_askedToStop.load() == 1;
+    return m_askedToStop.loadAcquire() == 1;
 }
 
 void IUnitedEntry::setOngoing(bool p_ongoing)
diff --git a/src/utils/asyncworker.cpp b/src/utils/asyncworker.cpp
index b4b59c6de7..7fc550746a 100644
--- a/src/utils/asyncworker.cpp
+++ b/src/utils/asyncworker.cpp
@@ -9,12 +9,12 @@ AsyncWorker::AsyncWorker(QObject *p_parent)
 
 void AsyncWorker::stop()
 {
-    m_askedToStop.store(1);
+    m_askedToStop.fetchAndStoreAcquire(1);
 }
 
 bool AsyncWorker::isAskedToStop() const
 {
-    return m_askedToStop.load() == 1;
+    return m_askedToStop.loadAcquire() == 1;
 }
 
 
diff --git a/src/utils/fileutils.cpp b/src/utils/fileutils.cpp
index cf62d38551..435bf30277 100644
--- a/src/utils/fileutils.cpp
+++ b/src/utils/fileutils.cpp
@@ -10,6 +10,7 @@
 #include <core/global.h>
 
 #include "pathutils.h"
+#include <QRandomGenerator>
 
 using namespace vnotex;
 
@@ -313,7 +314,7 @@ QString FileUtils::generateRandomFileName(const QString &p_hints, const QString
 
     // Do not use toSecsSinceEpoch() here since we want a short name.
     const QString timeStamp(QDateTime::currentDateTime().toString(QStringLiteral("sszzzmmHHyyMMdd")));
-    const QString baseName(QString::number(timeStamp.toLongLong() + qrand()));
+    const QString baseName(QString::number(timeStamp.toLongLong() + QRandomGenerator::global()->generate()));
 
     QString suffix;
     if (!p_suffix.isEmpty()) {
diff --git a/src/utils/htmlutils.cpp b/src/utils/htmlutils.cpp
index f1c439b8d1..935512c4df 100644
--- a/src/utils/htmlutils.cpp
+++ b/src/utils/htmlutils.cpp
@@ -1,13 +1,13 @@
 #include "htmlutils.h"
 
-#include <QRegExp>
+#include <QRegularExpression>
 
 using namespace vnotex;
 
 bool HtmlUtils::hasOnlyImgTag(const QString &p_html)
 {
     // Tricky.
-    QRegExp reg(QStringLiteral("<(?:p|span|div) "));
+    QRegularExpression reg(QStringLiteral("<(?:p|span|div) "));
     return !p_html.contains(reg);
 }
 
diff --git a/src/utils/iconutils.cpp b/src/utils/iconutils.cpp
index 90627de5bd..80ea617332 100644
--- a/src/utils/iconutils.cpp
+++ b/src/utils/iconutils.cpp
@@ -67,7 +67,7 @@ QString IconUtils::replaceForegroundOfIcon(const QString &p_iconContent, const Q
     }
 
     // Negative lookahead to avoid fill="none".
-    QRegExp styleRe(R"((\s|"|;)(fill|stroke)(:|(="))(?!none)[^;"]*)");
+    QRegularExpression styleRe(R"((\s|"|;)(fill|stroke)(:|(="))(?!none)[^;"]*)");
     if (p_iconContent.indexOf(styleRe) > -1) {
         auto newContent(p_iconContent);
         newContent.replace(styleRe, QString("\\1\\2\\3%1").arg(p_foreground));
@@ -85,7 +85,7 @@ bool IconUtils::isMonochrome(const QString &p_iconContent)
     QString lastColor = "";
     int pos = 0;
     while (pos < p_iconContent.size()) {
-        int idx = p_iconContent.indexOf(monoRe, pos);
+        int idx = monoRe.indexIn(p_iconContent, pos);
         if (idx == -1) {
             break;
         }
diff --git a/src/utils/printutils.cpp b/src/utils/printutils.cpp
index 72e48a13c7..0a1e9813e1 100644
--- a/src/utils/printutils.cpp
+++ b/src/utils/printutils.cpp
@@ -11,7 +11,7 @@ QSharedPointer<QPrinter> PrintUtils::promptForPrint(bool p_printSelectionEnabled
 
     QPrintDialog dialog(printer.data(), p_parent);
     if (p_printSelectionEnabled) {
-        dialog.addEnabledOption(QAbstractPrintDialog::PrintSelection);
+        dialog.setOption(QAbstractPrintDialog::PrintSelection);
     }
 
     if (dialog.exec() == QDialog::Accepted) {
diff --git a/src/utils/utils.cpp b/src/utils/utils.cpp
index e2c9155312..076722a0dc 100644
--- a/src/utils/utils.cpp
+++ b/src/utils/utils.cpp
@@ -42,7 +42,7 @@ void Utils::appendMsg(QString &p_msg, const QString &p_new)
 
 QString Utils::dateTimeString(const QDateTime &p_dateTime)
 {
-    return p_dateTime.date().toString(Qt::DefaultLocaleLongDate)
+    return p_dateTime.date().toString(Qt::ISODate)
            + " "
            + p_dateTime.time().toString(Qt::TextDate);
 }
diff --git a/src/utils/utils.pri b/src/utils/utils.pri
index a072a928df..b53ebf30f9 100644
--- a/src/utils/utils.pri
+++ b/src/utils/utils.pri
@@ -1,4 +1,4 @@
-QT += widgets svg
+QT += widgets svg core5compat
 
 SOURCES += \
     $$PWD/asyncworker.cpp \
diff --git a/src/utils/webutils.cpp b/src/utils/webutils.cpp
index 7069936b8b..46b1822156 100644
--- a/src/utils/webutils.cpp
+++ b/src/utils/webutils.cpp
@@ -58,7 +58,8 @@ QString WebUtils::toDataUri(const QUrl &p_url, bool p_keepTitle)
 
         if (!p_keepTitle) {
             // Remove <title>...</title>.
-            QRegExp reg("<title>.*</title>", Qt::CaseInsensitive);
+            QRegularExpression reg("<title>.*</title>");
+            reg.setPatternOptions(QRegularExpression::CaseInsensitiveOption);
             uri.remove(reg);
         }
     } else {
diff --git a/src/utils/widgetutils.cpp b/src/utils/widgetutils.cpp
index e9af368065..b9974b1e8b 100644
--- a/src/utils/widgetutils.cpp
+++ b/src/utils/widgetutils.cpp
@@ -6,7 +6,6 @@
 #include <QStyle>
 #include <QAbstractScrollArea>
 #include <QScrollBar>
-#include <QDesktopWidget>
 #include <QApplication>
 #include <QDesktopServices>
 #include <QKeyEvent>
@@ -71,8 +70,7 @@ bool WidgetUtils::isScrollBarVisible(QAbstractScrollArea *p_widget, bool p_horiz
 
 QSize WidgetUtils::availableScreenSize(QWidget *p_widget)
 {
-    auto geo = QApplication::desktop()->availableGeometry(p_widget);
-    return geo.size();
+    return p_widget->screen()->availableGeometry().size();
 }
 
 void WidgetUtils::openUrlByDesktop(const QUrl &p_url)
@@ -374,7 +372,7 @@ QString WidgetUtils::getMonospaceFont()
         for (const auto &candidate : candidates) {
             QString family = candidate.trimmed().toLower();
             for (auto availFamily : availFamilies) {
-                availFamily.remove(QRegExp("\\[.*\\]"));
+                availFamily.remove(QRegularExpression("\\[.*\\]"));
                 if (family == availFamily.trimmed().toLower()) {
                     font = availFamily;
                     return font;
diff --git a/src/widgets/dialogs/dialog.cpp b/src/widgets/dialogs/dialog.cpp
index a28524f33a..6c8cc1146f 100644
--- a/src/widgets/dialogs/dialog.cpp
+++ b/src/widgets/dialogs/dialog.cpp
@@ -3,7 +3,6 @@
 #include <QVBoxLayout>
 #include <QDebug>
 #include <QApplication>
-#include <QDesktopWidget>
 #include <QScrollBar>
 #include <QTimer>
 #include <QPlainTextEdit>
diff --git a/src/widgets/dialogs/imageinsertdialog.cpp b/src/widgets/dialogs/imageinsertdialog.cpp
index 95b7e3189a..c75d2f09a5 100644
--- a/src/widgets/dialogs/imageinsertdialog.cpp
+++ b/src/widgets/dialogs/imageinsertdialog.cpp
@@ -6,7 +6,7 @@
 #include <QRegularExpression>
 #include <QLabel>
 #include <QPushButton>
-#include <QRegExpValidator>
+#include <QRegularExpressionValidator>
 #include <QSpinBox>
 #include <QSlider>
 #include <QScrollArea>
@@ -88,7 +88,7 @@ void ImageInsertDialog::setupUI(const QString &p_title,
 
     // Image Title.
     m_imageTitleEdit = WidgetsFactory::createLineEdit(p_imageTitle, mainWidget);
-    auto titleValidator = new QRegExpValidator(QRegExp(vte::MarkdownUtils::c_imageTitleRegExp), m_imageTitleEdit);
+    auto titleValidator = new QRegularExpressionValidator(QRegularExpression(vte::MarkdownUtils::c_imageTitleRegExp), m_imageTitleEdit);
     m_imageTitleEdit->setValidator(titleValidator);
     gridLayout->addWidget(new QLabel(tr("Title:"), mainWidget), 1, 0, 1, 1);
     gridLayout->addWidget(m_imageTitleEdit, 1, 1, 1, 3);
@@ -97,7 +97,7 @@ void ImageInsertDialog::setupUI(const QString &p_title,
 
     // Image Alt.
     m_imageAltEdit = WidgetsFactory::createLineEdit(p_imageAlt, mainWidget);
-    auto altValidator = new QRegExpValidator(QRegExp(vte::MarkdownUtils::c_imageAltRegExp), m_imageAltEdit);
+    auto altValidator = new QRegularExpressionValidator(QRegularExpression(vte::MarkdownUtils::c_imageAltRegExp), m_imageAltEdit);
     m_imageAltEdit->setValidator(altValidator);
     gridLayout->addWidget(new QLabel(tr("Alt text:"), mainWidget), 2, 0, 1, 1);
     gridLayout->addWidget(m_imageAltEdit, 2, 1, 1, 3);
diff --git a/src/widgets/dialogs/scrolldialog.cpp b/src/widgets/dialogs/scrolldialog.cpp
index f4921fd497..d668871960 100644
--- a/src/widgets/dialogs/scrolldialog.cpp
+++ b/src/widgets/dialogs/scrolldialog.cpp
@@ -4,7 +4,6 @@
 #include <QVBoxLayout>
 #include <QDebug>
 #include <QApplication>
-#include <QDesktopWidget>
 #include <QScrollBar>
 #include <QTimer>
 #include <QPlainTextEdit>
diff --git a/src/widgets/dialogs/selectdialog.cpp b/src/widgets/dialogs/selectdialog.cpp
index c1846ca2a9..62d5f88c62 100644
--- a/src/widgets/dialogs/selectdialog.cpp
+++ b/src/widgets/dialogs/selectdialog.cpp
@@ -73,7 +73,7 @@ void SelectDialog::addSelection(const QString &p_selectStr, int p_selectID)
     QChar shortcut;
     if (m_nextShortcut < c_cancelShortcut) {
         shortcut = m_nextShortcut;
-        m_nextShortcut = m_nextShortcut.toLatin1() + 1;
+        m_nextShortcut = QChar(m_nextShortcut.toLatin1() + 1);
     }
     const auto icon = IconUtils::drawTextIcon(shortcut, m_shortcutIconForeground, m_shortcutIconBorder);
     QListWidgetItem *item = new QListWidgetItem(icon, p_selectStr);
diff --git a/src/widgets/dialogs/settings/fileassociationpage.cpp b/src/widgets/dialogs/settings/fileassociationpage.cpp
index 5245b7436e..d59dbb481d 100644
--- a/src/widgets/dialogs/settings/fileassociationpage.cpp
+++ b/src/widgets/dialogs/settings/fileassociationpage.cpp
@@ -64,7 +64,7 @@ bool FileAssociationPage::saveInternal()
         if (name.isEmpty()) {
             continue;
         }
-        auto suffixes = lineEdit->text().split(c_suffixSeparator, QString::SkipEmptyParts);
+        auto suffixes = lineEdit->text().split(c_suffixSeparator, Qt::SkipEmptyParts);
         fileTypeSuffixes.push_back(CoreConfig::FileTypeSuffix(name, Utils::toLower(suffixes)));
     }
 
diff --git a/src/widgets/dialogs/sortdialog.cpp b/src/widgets/dialogs/sortdialog.cpp
index 3deac97706..2836021841 100644
--- a/src/widgets/dialogs/sortdialog.cpp
+++ b/src/widgets/dialogs/sortdialog.cpp
@@ -110,7 +110,7 @@ void SortDialog::updateTreeWidget()
         item->setFlags(item->flags() & ~Qt::ItemIsDropEnabled);
     }
 
-    m_treeWidget->sortByColumn(-1);
+    m_treeWidget->sortByColumn(-1, Qt::AscendingOrder);
     m_treeWidget->setSortingEnabled(true);
 }
 
@@ -151,7 +151,7 @@ void SortDialog::handleMoveOperation(MoveOperation p_op)
     Q_ASSERT(first <= last && (last - first + 1) == selectedItems.size());
     QTreeWidgetItem *firstItem = nullptr;
 
-    m_treeWidget->sortByColumn(-1);
+    m_treeWidget->sortByColumn(-1, Qt::AscendingOrder);
 
     switch (p_op) {
     case MoveOperation::Top:
diff --git a/src/widgets/dialogs/tableinsertdialog.cpp b/src/widgets/dialogs/tableinsertdialog.cpp
index 92ac28dfbc..fc653fd9db 100644
--- a/src/widgets/dialogs/tableinsertdialog.cpp
+++ b/src/widgets/dialogs/tableinsertdialog.cpp
@@ -63,7 +63,9 @@ void TableInsertDialog::setupUI(const QString &p_title)
         buttonGroup->addButton(rightBtn, static_cast<int>(Alignment::Right));
 
         noneBtn->setChecked(true);
-        connect(buttonGroup, static_cast<void(QButtonGroup::*)(int, bool)>(&QButtonGroup::buttonToggled),
+        connect(buttonGroup, (void(QButtonGroup::*)(int, bool))(&QButtonGroup::buttonToggled),
+
+
                 this, [this](int p_id, bool p_checked){
                     if (p_checked) {
                         m_alignment = static_cast<Alignment>(p_id);
diff --git a/src/widgets/editors/markdowneditor.cpp b/src/widgets/editors/markdowneditor.cpp
index 5ae3a422c6..c9bb5c5f8a 100644
--- a/src/widgets/editors/markdowneditor.cpp
+++ b/src/widgets/editors/markdowneditor.cpp
@@ -55,6 +55,7 @@
 #include <imagehost/imagehostutils.h>
 #include <imagehost/imagehost.h>
 #include <imagehost/imagehostmgr.h>
+#include <QRegExp>
 
 #include "previewhelper.h"
 #include "../outlineprovider.h"
@@ -1198,7 +1199,7 @@ void MarkdownEditor::handleHtmlToMarkdownData(quint64 p_id, TimeStamp p_timeStam
 
 static QString purifyImageTitle(QString p_title)
 {
-    return p_title.remove(QRegExp("[\\r\\n\\[\\]]"));
+    return p_title.remove(QRegularExpression("[\\r\\n\\[\\]]"));
 }
 
 void MarkdownEditor::fetchImagesToLocalAndReplace(QString &p_text)
diff --git a/src/widgets/editors/markdowntable.cpp b/src/widgets/editors/markdowntable.cpp
index c789b750b9..93c9b05127 100644
--- a/src/widgets/editors/markdowntable.cpp
+++ b/src/widgets/editors/markdowntable.cpp
@@ -214,10 +214,10 @@ void MarkdownTable::initWidths(const QTextBlock &p_block, int p_borderPos)
     }
 
     QFontMetricsF fmf(font);
-    s_spaceWidth = fmf.width(' ');
-    s_minusWidth = fmf.width('-');
-    s_colonWidth = fmf.width(':');
-    s_defaultDelimiterWidth = fmf.width(c_defaultDelimiter);
+    s_spaceWidth = fmf.horizontalAdvance(' ');
+    s_minusWidth = fmf.horizontalAdvance('-');
+    s_colonWidth = fmf.horizontalAdvance(':');
+    s_defaultDelimiterWidth = fmf.horizontalAdvance(c_defaultDelimiter);
 
     qDebug() << "smart table widths" << font.family() << s_spaceWidth << s_minusWidth << s_colonWidth << s_defaultDelimiterWidth;
 }
diff --git a/src/widgets/editors/markdownviewer.cpp b/src/widgets/editors/markdownviewer.cpp
index 2a5412d3f4..a75a9a6827 100644
--- a/src/widgets/editors/markdownviewer.cpp
+++ b/src/widgets/editors/markdownviewer.cpp
@@ -108,7 +108,7 @@ void MarkdownViewer::setPreviewHelper(PreviewHelper *p_previewHelper)
 
 void MarkdownViewer::contextMenuEvent(QContextMenuEvent *p_event)
 {
-    QScopedPointer<QMenu> menu(page()->createStandardContextMenu());
+    QScopedPointer<QMenu> menu(this->createStandardContextMenu());
     const QList<QAction *> actions = menu->actions();
 
 #if defined(Q_OS_WIN)
diff --git a/src/widgets/editors/previewhelper.cpp b/src/widgets/editors/previewhelper.cpp
index dc061d88e5..1447a48bce 100644
--- a/src/widgets/editors/previewhelper.cpp
+++ b/src/widgets/editors/previewhelper.cpp
@@ -338,7 +338,7 @@ void PreviewHelper::updateEditorInplacePreviewCodeBlock()
     m_previousInplacePreviewCodeBlockSize = previewItems.size();
 
     if (!obsoleteBlocks.isEmpty()) {
-        emit potentialObsoletePreviewBlocksUpdated(obsoleteBlocks.toList());
+        emit potentialObsoletePreviewBlocksUpdated(obsoleteBlocks.values());
     }
 
     m_codeBlockCache.setCapacityHint(m_codeBlocksData.size());
@@ -434,7 +434,7 @@ void PreviewHelper::updateEditorInplacePreviewMathBlock()
     m_previousInplacePreviewMathBlockSize = previewItems.size();
 
     if (!obsoleteBlocks.isEmpty()) {
-        emit potentialObsoletePreviewBlocksUpdated(obsoleteBlocks.toList());
+        emit potentialObsoletePreviewBlocksUpdated(obsoleteBlocks.values());
     }
 
     m_mathBlockCache.setCapacityHint(m_mathBlocksData.size());
diff --git a/src/widgets/fullscreentoggleaction.cpp b/src/widgets/fullscreentoggleaction.cpp
index 7ab356fa88..b84bcf6b45 100644
--- a/src/widgets/fullscreentoggleaction.cpp
+++ b/src/widgets/fullscreentoggleaction.cpp
@@ -1,6 +1,7 @@
 #include "fullscreentoggleaction.h"
 
 #include <QEvent>
+#include <QWidget>
 
 using namespace vnotex;
 
diff --git a/src/widgets/labelwithbuttonswidget.cpp b/src/widgets/labelwithbuttonswidget.cpp
index 8f23eff8e1..918763d0aa 100644
--- a/src/widgets/labelwithbuttonswidget.cpp
+++ b/src/widgets/labelwithbuttonswidget.cpp
@@ -45,7 +45,7 @@ void LabelWithButtonsWidget::paintEvent(QPaintEvent *p_event)
     Q_UNUSED(p_event);
 
     QStyleOption opt;
-    opt.init(this);
+    opt.initFrom(this);
     QPainter p(this);
     style()->drawPrimitive(QStyle::PE_Widget, &opt, &p, this);
 }
diff --git a/src/widgets/markdownviewwindow.cpp b/src/widgets/markdownviewwindow.cpp
index 584af6db2d..3242bdcde9 100644
--- a/src/widgets/markdownviewwindow.cpp
+++ b/src/widgets/markdownviewwindow.cpp
@@ -13,6 +13,7 @@
 #include <QActionGroup>
 #include <QTimer>
 #include <QPrinter>
+  #include <QWebEngineSettings>
 
 #include <core/fileopenparameters.h>
 #include <core/editorconfig.h>
@@ -394,6 +395,8 @@ void MarkdownViewWindow::setupTextEditor()
 
     connect(m_editor, &MarkdownEditor::applySnippetRequested,
             this, QOverload<>::of(&MarkdownViewWindow::applySnippet));
+    connect(m_viewer, &MarkdownViewer::printFinished, this, &MarkdownViewWindow::onPrintFinish);
+
 }
 
 QStackedWidget *MarkdownViewWindow::getMainStatusWidget() const
@@ -502,6 +505,7 @@ void MarkdownViewWindow::setupViewer()
                     setEditViewMode(m_editViewMode);
                 }
             });
+    m_viewer->settings()->resetAttribute(QWebEngineSettings::LocalContentCanAccessRemoteUrls);
 }
 
 void MarkdownViewWindow::syncTextEditorFromBuffer(bool p_syncPositionFromReadMode)
@@ -1398,15 +1402,31 @@ void MarkdownViewWindow::print()
         return;
     }
 
-    auto printer = PrintUtils::promptForPrint(m_viewer->hasSelection(), this);
-    if (printer) {
-        m_viewer->page()->print(printer.data(), [printer](bool p_succeeded) mutable {
-                    Q_UNUSED(p_succeeded);
-                    printer.reset();
-                });
+    m_printer = PrintUtils::promptForPrint(m_viewer->hasSelection(), this);
+
+    if (m_printer)
+    {
+        m_printer->setOutputFormat(QPrinter::PdfFormat);
+        m_viewer->print(m_printer.get());
     }
 }
+void MarkdownViewWindow::onPrintFinish(bool isSeccess)
+{
+    m_printer.reset();
+    QString message;
+    if (isSeccess) {
+         message = "print to pdf suceess.";
+    } else {
+         message = "print to pdf failed.";
+    }
+    showMessage(message);
 
+//    MessageBoxHelper::notify(MessageBoxHelper::Information,
+//                             message,
+//                             QString(),
+//                             QString(),
+//                             this);
+}
 void MarkdownViewWindow::handleExternalCodeBlockHighlightRequest(int p_idx, quint64 p_timeStamp, const QString &p_text)
 {
     static bool stylesInitialized = false;
diff --git a/src/widgets/markdownviewwindow.h b/src/widgets/markdownviewwindow.h
index eecbbe72ce..11d72db9d9 100644
--- a/src/widgets/markdownviewwindow.h
+++ b/src/widgets/markdownviewwindow.h
@@ -12,7 +12,7 @@ class QStackedWidget;
 class QWebEngineView;
 class QActionGroup;
 class QTimer;
-
+class QPrinter;
 namespace vte
 {
     class MarkdownEditorConfig;
@@ -61,6 +61,7 @@ namespace vnotex
     public slots:
         void handleEditorConfigChange() Q_DECL_OVERRIDE;
 
+        void onPrintFinish(bool isSeccess);
     protected slots:
         void setModified(bool p_modified) Q_DECL_OVERRIDE;
 
@@ -237,6 +238,7 @@ namespace vnotex
         MarkdownEditorConfig::EditViewMode m_editViewMode = MarkdownEditorConfig::EditViewMode::EditOnly;
 
         QTimer *m_syncPreviewTimer = nullptr;
+        QSharedPointer<QPrinter> m_printer;
     };
 }
 
diff --git a/src/widgets/navigationmode.cpp b/src/widgets/navigationmode.cpp
index 4fdc13aafa..353561e59c 100644
--- a/src/widgets/navigationmode.cpp
+++ b/src/widgets/navigationmode.cpp
@@ -74,7 +74,7 @@ static QString generateNavigationLabelStyle(const QString &p_str, bool p_tiny)
         QFont font(fontFamily, fontPt);
         font.setBold(true);
         QFontMetrics fm(font);
-        pxWidth = fm.width(p_str) + 5;
+        pxWidth = fm.horizontalAdvance(p_str) + 5;
         pxHeight = fm.capHeight() + 5;
         lastLen = p_str.size();
     }
diff --git a/src/widgets/notebookexplorersession.cpp b/src/widgets/notebookexplorersession.cpp
index 7c1cf16f5f..546c35048c 100644
--- a/src/widgets/notebookexplorersession.cpp
+++ b/src/widgets/notebookexplorersession.cpp
@@ -1,4 +1,5 @@
 #include "notebookexplorersession.h"
+#include <QIODevice>
 
 using namespace vnotex;
 
diff --git a/src/widgets/outlineprovider.h b/src/widgets/outlineprovider.h
index 7719b54e4f..39dae2424d 100644
--- a/src/widgets/outlineprovider.h
+++ b/src/widgets/outlineprovider.h
@@ -4,7 +4,7 @@
 #include <QObject>
 #include <QSharedPointer>
 #include <QVector>
-
+#include <limits.h>
 namespace vnotex
 {
     typedef QVector<int> SectionNumber;
diff --git a/src/widgets/quickselector.cpp b/src/widgets/quickselector.cpp
index 0ac4657dfe..785e9c3680 100644
--- a/src/widgets/quickselector.cpp
+++ b/src/widgets/quickselector.cpp
@@ -194,7 +194,7 @@ void QuickSelector::searchAndFilter(const QString &p_text)
     }
 
     // Check name.
-    auto parts = text.split(QLatin1Char(' '), QString::SkipEmptyParts);
+    auto parts = text.split(QLatin1Char(' '), Qt::SkipEmptyParts);
     Q_ASSERT(!parts.isEmpty());
     QRegularExpression regExp;
     regExp.setPatternOptions(regExp.patternOptions() | QRegularExpression::CaseInsensitiveOption);
diff --git a/src/widgets/titlebar.cpp b/src/widgets/titlebar.cpp
index 5077624e42..124e7ff0c5 100644
--- a/src/widgets/titlebar.cpp
+++ b/src/widgets/titlebar.cpp
@@ -99,9 +99,9 @@ void TitleBar::setupActionButtons(TitleBar::Actions p_actionFlags)
     }
 }
 
-void TitleBar::enterEvent(QEvent *p_event)
+void TitleBar::enterEvent(QEnterEvent *p_event)
 {
-    QWidget::enterEvent(p_event);
+    QFrame::enterEvent(p_event);
     setActionButtonsVisible(true);
 }
 
diff --git a/src/widgets/titlebar.h b/src/widgets/titlebar.h
index 6dc71fb6be..258f6baf0a 100644
--- a/src/widgets/titlebar.h
+++ b/src/widgets/titlebar.h
@@ -53,7 +53,7 @@ namespace vnotex
         void setActionButtonsAlwaysShown(bool p_shown);
 
     protected:
-        void enterEvent(QEvent *p_event) Q_DECL_OVERRIDE;
+        void enterEvent(QEnterEvent *p_event) Q_DECL_OVERRIDE;
 
         void leaveEvent(QEvent *p_event) Q_DECL_OVERRIDE;
 
diff --git a/src/widgets/toolbox.cpp b/src/widgets/toolbox.cpp
index 9ad4e14011..9945e54dda 100644
--- a/src/widgets/toolbox.cpp
+++ b/src/widgets/toolbox.cpp
@@ -13,6 +13,7 @@
 #include <utils/iconutils.h>
 #include "thememgr.h"
 #include "vnotex.h"
+#include <QActionGroup>
 
 using namespace vnotex;