diff --git a/src/core/editorconfig.h b/src/core/editorconfig.h
index a81a79ac..0e6b2426 100644
--- a/src/core/editorconfig.h
+++ b/src/core/editorconfig.h
@@ -61,6 +61,7 @@ namespace vnotex
             Tag,
             Debug,
             Print,
+            ClearHighlights,
             MaxShortcut
         };
         Q_ENUM(Shortcut)
diff --git a/src/core/htmltemplatehelper.cpp b/src/core/htmltemplatehelper.cpp
index 6321b3ee..d661cb4c 100644
--- a/src/core/htmltemplatehelper.cpp
+++ b/src/core/htmltemplatehelper.cpp
@@ -20,6 +20,7 @@ QString WebGlobalOptions::toJavascriptObject() const
 {
     return QStringLiteral("window.vxOptions = {\n")
            + QString("webPlantUml: %1,\n").arg(Utils::boolToString(m_webPlantUml))
+           + QString("plantUmlWebService: '%1',\n").arg(m_plantUmlWebService)
            + QString("webGraphviz: %1,\n").arg(Utils::boolToString(m_webGraphviz))
            + QString("mathJaxScript: '%1',\n").arg(m_mathJaxScript)
            + QString("constrainImageWidthEnabled: %1,\n").arg(Utils::boolToString(m_constrainImageWidthEnabled))
@@ -213,6 +214,7 @@ QString HtmlTemplateHelper::generateMarkdownViewerTemplate(const MarkdownEditorC
     {
         WebGlobalOptions opts;
         opts.m_webPlantUml = p_config.getWebPlantUml();
+        opts.m_plantUmlWebService = p_config.getPlantUmlWebService();
         opts.m_webGraphviz = p_config.getWebGraphviz();
         opts.m_mathJaxScript = p_config.getMathJaxScript();
         opts.m_sectionNumberEnabled = p_config.getSectionNumberMode() == MarkdownEditorConfig::SectionNumberMode::Read;
diff --git a/src/core/htmltemplatehelper.h b/src/core/htmltemplatehelper.h
index b725812f..9eba5d02 100644
--- a/src/core/htmltemplatehelper.h
+++ b/src/core/htmltemplatehelper.h
@@ -13,6 +13,8 @@ namespace vnotex
     {
         bool m_webPlantUml = true;
 
+        QString m_plantUmlWebService;
+
         bool m_webGraphviz = true;
 
         QString m_mathJaxScript;
diff --git a/src/core/markdowneditorconfig.cpp b/src/core/markdowneditorconfig.cpp
index 7fd26cc8..7b6cef9c 100644
--- a/src/core/markdowneditorconfig.cpp
+++ b/src/core/markdowneditorconfig.cpp
@@ -35,6 +35,8 @@ void MarkdownEditorConfig::init(const QJsonObject &p_app, const QJsonObject &p_u
 
     m_plantUmlCommand = READSTR(QStringLiteral("plantuml_command"));
 
+    m_plantUmlWebService = READSTR(QStringLiteral("plantuml_web_service"));
+
     m_webGraphviz = READBOOL(QStringLiteral("web_graphviz"));
 
     m_graphvizExe = READSTR(QStringLiteral("graphviz_exe"));
@@ -90,6 +92,7 @@ QJsonObject MarkdownEditorConfig::toJson() const
     obj[QStringLiteral("web_plantuml")] = m_webPlantUml;
     obj[QStringLiteral("plantuml_jar")] = m_plantUmlJar;
     obj[QStringLiteral("plantuml_command")] = m_plantUmlCommand;
+    obj[QStringLiteral("plantuml_web_service")] = m_plantUmlWebService;
     obj[QStringLiteral("web_graphviz")] = m_webGraphviz;
     obj[QStringLiteral("graphviz_exe")] = m_graphvizExe;
     obj[QStringLiteral("mathjax_script")] = m_mathJaxScript;
@@ -238,6 +241,16 @@ const QString &MarkdownEditorConfig::getPlantUmlCommand() const
     return m_plantUmlCommand;
 }
 
+const QString &MarkdownEditorConfig::getPlantUmlWebService() const
+{
+    return m_plantUmlWebService;
+}
+
+void MarkdownEditorConfig::setPlantUmlWebService(const QString &p_service)
+{
+    updateConfig(m_plantUmlWebService, p_service, this);
+}
+
 bool MarkdownEditorConfig::getWebGraphviz() const
 {
     return m_webGraphviz;
@@ -280,9 +293,7 @@ bool MarkdownEditorConfig::getConfirmBeforeClearObsoleteImages() const
 
 void MarkdownEditorConfig::setConfirmBeforeClearObsoleteImages(bool p_confirm)
 {
-    updateConfig(m_confirmBeforeClearObsoleteImages,
-                 p_confirm,
-                 this);
+    updateConfig(m_confirmBeforeClearObsoleteImages, p_confirm, this);
 }
 
 bool MarkdownEditorConfig::getInsertFileNameAsTitle() const
diff --git a/src/core/markdowneditorconfig.h b/src/core/markdowneditorconfig.h
index 9cbead37..97d2701c 100644
--- a/src/core/markdowneditorconfig.h
+++ b/src/core/markdowneditorconfig.h
@@ -70,6 +70,9 @@ namespace vnotex
 
         const QString &getPlantUmlCommand() const;
 
+        const QString &getPlantUmlWebService() const;
+        void setPlantUmlWebService(const QString &p_service);
+
         bool getWebGraphviz() const;
         void setWebGraphviz(bool p_enabled);
 
@@ -185,6 +188,9 @@ namespace vnotex
         // %1: the format to render in.
         QString m_plantUmlCommand;
 
+        // PlantUml Web service to override that in plantuml.js file.
+        QString m_plantUmlWebService;
+
         bool m_webGraphviz = true;
 
         // Graphviz executable file.
diff --git a/src/data/core/vnotex.json b/src/data/core/vnotex.json
index 41cfe8f9..36e75770 100644
--- a/src/data/core/vnotex.json
+++ b/src/data/core/vnotex.json
@@ -208,7 +208,8 @@
                 "ApplySnippet" : "Ctrl+G, I",
                 "Tag" : "Ctrl+G, B",
                 "Debug" : "F12",
-                "Print" : ""
+                "Print" : "",
+                "ClearHighlights" : "Ctrl+G, Space"
             },
             "spell_check_auto_detect_language" : false,
             "spell_check_default_dictionary" : "en_US",
@@ -401,6 +402,8 @@
             "//commnet" : "Command to render PlantUML via stdin and stdout (overrides plantuml_jar)",
             "//commnet" : "- %1: the format to render in",
             "plantuml_command" : "",
+            "//commnet" : "PlantUml Web service to use",
+            "plantuml_web_service" : "",
             "//comment" : "Whether use javascript or external program to render Graphviz",
             "web_graphviz" : true,
             "//commnet" : "Local Graphviz executable file to render Graphviz",
diff --git a/src/data/extra/web/js/plantuml.js b/src/data/extra/web/js/plantuml.js
index fb981958..af2ae798 100644
--- a/src/data/extra/web/js/plantuml.js
+++ b/src/data/extra/web/js/plantuml.js
@@ -34,6 +34,18 @@ class PlantUml extends GraphRenderer {
         }
     }
 
+    initialize(p_callback) {
+        if (super.initialized) {
+            return true;
+        }
+
+        if (!!window.vxOptions.plantUmlWebService) {
+            this.serverUrl = window.vxOptions.plantUmlWebService;
+            console.log('override PlantUml Web service', this.serverUrl);
+        }
+
+        return super.initialize(p_callback);
+    }
 
     // Interface 1.
     render(p_node, p_format) {
diff --git a/src/widgets/dialogs/settings/fileassociationpage.cpp b/src/widgets/dialogs/settings/fileassociationpage.cpp
index 0ea114b0..a19e7e89 100644
--- a/src/widgets/dialogs/settings/fileassociationpage.cpp
+++ b/src/widgets/dialogs/settings/fileassociationpage.cpp
@@ -62,7 +62,7 @@ bool FileAssociationPage::saveInternal()
         if (name.isEmpty()) {
             continue;
         }
-        auto suffixes = lineEdit->text().split(c_suffixSeparator, Qt::SkipEmptyParts);
+        auto suffixes = lineEdit->text().split(c_suffixSeparator, QString::SkipEmptyParts);
         fileTypeSuffixes.push_back(CoreConfig::FileTypeSuffix(name, Utils::toLower(suffixes)));
     }
 
diff --git a/src/widgets/dialogs/settings/markdowneditorpage.cpp b/src/widgets/dialogs/settings/markdowneditorpage.cpp
index 53dd596d..e167ea91 100644
--- a/src/widgets/dialogs/settings/markdowneditorpage.cpp
+++ b/src/widgets/dialogs/settings/markdowneditorpage.cpp
@@ -104,6 +104,8 @@ void MarkdownEditorPage::loadInternal()
 
     m_plantUmlJarFileInput->setText(markdownConfig.getPlantUmlJar());
 
+    m_plantUmlWebServiceLineEdit->setText(markdownConfig.getPlantUmlWebService());
+
     {
         int idx = m_graphvizModeComboBox->findData(markdownConfig.getWebGraphviz() ? 0 : 1);
         m_graphvizModeComboBox->setCurrentIndex(idx);
@@ -189,6 +191,8 @@ bool MarkdownEditorPage::saveInternal()
 
     markdownConfig.setPlantUmlJar(m_plantUmlJarFileInput->text());
 
+    markdownConfig.setPlantUmlWebService(m_plantUmlWebServiceLineEdit->text());
+
     markdownConfig.setWebGraphviz(m_graphvizModeComboBox->currentData().toInt() == 0);
 
     markdownConfig.setGraphvizExe(m_graphvizFileInput->text());
@@ -468,9 +472,9 @@ QGroupBox *MarkdownEditorPage::setupGeneralGroup()
 
     {
         m_plantUmlModeComboBox = WidgetsFactory::createComboBox(box);
-        m_plantUmlModeComboBox->setToolTip(tr("Use online service or local JAR file to render PlantUml graphs"));
+        m_plantUmlModeComboBox->setToolTip(tr("Use Web service or local JAR file to render PlantUml graphs"));
 
-        m_plantUmlModeComboBox->addItem(tr("Online Service"), 0);
+        m_plantUmlModeComboBox->addItem(tr("Web Service"), 0);
         m_plantUmlModeComboBox->addItem(tr("Local JAR"), 1);
 
         const QString label(tr("PlantUml:"));
@@ -527,10 +531,21 @@ QGroupBox *MarkdownEditorPage::setupGeneralGroup()
     }
 
     {
-        m_graphvizModeComboBox = WidgetsFactory::createComboBox(box);
-        m_graphvizModeComboBox->setToolTip(tr("Use online service or local executable file to render Graphviz graphs"));
+        m_plantUmlWebServiceLineEdit = WidgetsFactory::createLineEdit(box);
+        m_plantUmlWebServiceLineEdit->setToolTip(tr("Override the Web service used to render PlantUml graphs"));
 
-        m_graphvizModeComboBox->addItem(tr("Online Service"), 0);
+        const QString label(tr("PlantUml Web service:"));
+        layout->addRow(label, m_plantUmlWebServiceLineEdit);
+        addSearchItem(label, m_plantUmlWebServiceLineEdit->toolTip(), m_plantUmlWebServiceLineEdit);
+        connect(m_plantUmlWebServiceLineEdit, &QLineEdit::textChanged,
+                this, &MarkdownEditorPage::pageIsChanged);
+    }
+
+    {
+        m_graphvizModeComboBox = WidgetsFactory::createComboBox(box);
+        m_graphvizModeComboBox->setToolTip(tr("Use Web service or local executable file to render Graphviz graphs"));
+
+        m_graphvizModeComboBox->addItem(tr("Web Service"), 0);
         m_graphvizModeComboBox->addItem(tr("Local Executable"), 1);
 
         const QString label(tr("Graphviz:"));
diff --git a/src/widgets/dialogs/settings/markdowneditorpage.h b/src/widgets/dialogs/settings/markdowneditorpage.h
index 4b689523..8f65c95c 100644
--- a/src/widgets/dialogs/settings/markdowneditorpage.h
+++ b/src/widgets/dialogs/settings/markdowneditorpage.h
@@ -79,6 +79,8 @@ namespace vnotex
 
         LocationInputWithBrowseButton *m_plantUmlJarFileInput = nullptr;
 
+        QLineEdit *m_plantUmlWebServiceLineEdit = nullptr;
+
         QComboBox *m_graphvizModeComboBox = nullptr;
 
         LocationInputWithBrowseButton *m_graphvizFileInput = nullptr;
diff --git a/src/widgets/dialogs/settings/settingsdialog.cpp b/src/widgets/dialogs/settings/settingsdialog.cpp
index 7d2c20be..4aeff09a 100644
--- a/src/widgets/dialogs/settings/settingsdialog.cpp
+++ b/src/widgets/dialogs/settings/settingsdialog.cpp
@@ -13,6 +13,8 @@
 #include <widgets/lineedit.h>
 #include <widgets/widgetsfactory.h>
 #include <widgets/propertydefs.h>
+#include <widgets/messageboxhelper.h>
+#include <widgets/mainwindow.h>
 #include <utils/widgetutils.h>
 #include <core/vnotex.h>
 
@@ -37,6 +39,9 @@ SettingsDialog::SettingsDialog(QWidget *p_parent)
     setupUI();
 
     setupPages();
+
+    connect(this, &QDialog::finished,
+            this, &SettingsDialog::checkOnFinish);
 }
 
 void SettingsDialog::setupUI()
@@ -315,3 +320,25 @@ void SettingsDialog::search()
             return true;
         });
 }
+
+void SettingsDialog::checkOnFinish()
+{
+    // Check whether need to prompt for restart.
+    forEachPage([this](const SettingsPage *p_page) {
+        if (p_page->isRestartNeeded()) {
+            // Restart VNote.
+            int ret = MessageBoxHelper::questionYesNo(MessageBoxHelper::Type::Information,
+                                                      tr("A restart of VNote may be needed to make changes take effect. Restart VNote now?"),
+                                                      QString(),
+                                                      QString(),
+                                                      this);
+            if (ret == QMessageBox::Yes) {
+                QMetaObject::invokeMethod(VNoteX::getInst().getMainWindow(),
+                                          &MainWindow::restart,
+                                          Qt::QueuedConnection);
+            }
+            return false;
+        }
+        return true;
+    });
+}
diff --git a/src/widgets/dialogs/settings/settingsdialog.h b/src/widgets/dialogs/settings/settingsdialog.h
index 545dc84f..fa567bfe 100644
--- a/src/widgets/dialogs/settings/settingsdialog.h
+++ b/src/widgets/dialogs/settings/settingsdialog.h
@@ -53,6 +53,8 @@ namespace vnotex
 
         void search();
 
+        void checkOnFinish();
+
         QLineEdit *m_searchEdit = nullptr;
 
         TreeWidget *m_pageExplorer = nullptr;
diff --git a/src/widgets/dialogs/settings/settingspage.cpp b/src/widgets/dialogs/settings/settingspage.cpp
index 3a906849..34a895d9 100644
--- a/src/widgets/dialogs/settings/settingspage.cpp
+++ b/src/widgets/dialogs/settings/settingspage.cpp
@@ -78,6 +78,8 @@ bool SettingsPage::save()
 
     if (saveInternal()) {
         m_changed = false;
+        // TODO: may need finer-grain check.
+        m_restartNeeded = true;
         return true;
     }
 
@@ -102,3 +104,8 @@ void SettingsPage::setError(const QString &p_err)
 {
     m_error = p_err;
 }
+
+bool SettingsPage::isRestartNeeded() const
+{
+    return m_restartNeeded;
+}
diff --git a/src/widgets/dialogs/settings/settingspage.h b/src/widgets/dialogs/settings/settingspage.h
index 937fce22..fe663f69 100644
--- a/src/widgets/dialogs/settings/settingspage.h
+++ b/src/widgets/dialogs/settings/settingspage.h
@@ -25,6 +25,8 @@ namespace vnotex
 
         const QString &error() const;
 
+        bool isRestartNeeded() const;
+
     signals:
         void changed();
 
@@ -64,6 +66,8 @@ namespace vnotex
 
         bool m_changed = false;
 
+        bool m_restartNeeded = false;
+
         QString m_error;
     };
 }
diff --git a/src/widgets/mainwindow.cpp b/src/widgets/mainwindow.cpp
index 77609fe6..ab9f1702 100644
--- a/src/widgets/mainwindow.cpp
+++ b/src/widgets/mainwindow.cpp
@@ -389,6 +389,7 @@ void MainWindow::closeEvent(QCloseEvent *p_event)
                 showNormal();
             }
         }
+
         saveStateAndGeometry();
     }
 
@@ -408,6 +409,8 @@ void MainWindow::closeEvent(QCloseEvent *p_event)
         FramelessMainWindowImpl::closeEvent(p_event);
         qApp->exit(exitCode > -1 ? exitCode : 0);
     } else {
+        emit minimizedToSystemTray();
+
         hide();
         p_event->ignore();
         if (needShowMessage) {
diff --git a/src/widgets/mainwindow.h b/src/widgets/mainwindow.h
index 8175c007..5b6ef2af 100644
--- a/src/widgets/mainwindow.h
+++ b/src/widgets/mainwindow.h
@@ -85,6 +85,8 @@ namespace vnotex
         // @m_response of @p_event: true to continue the close, false to stop the close.
         void mainWindowClosed(const QSharedPointer<Event> &p_event);
 
+        void minimizedToSystemTray();
+
         // No user interaction is available.
         void mainWindowClosedOnQuit();
 
diff --git a/src/widgets/markdownviewwindow.cpp b/src/widgets/markdownviewwindow.cpp
index f982a13f..06052209 100644
--- a/src/widgets/markdownviewwindow.cpp
+++ b/src/widgets/markdownviewwindow.cpp
@@ -1025,10 +1025,19 @@ void MarkdownViewWindow::handleReplaceAll(const QString &p_text, FindOptions p_o
 
 void MarkdownViewWindow::handleFindAndReplaceWidgetClosed()
 {
-    if (m_editor) {
-        TextViewWindowHelper::handleFindAndReplaceWidgetClosed(this);
-    } else {
+    if (isReadMode()) {
         adapter()->findText(QStringList(), FindOption::FindNone);
+    } else {
+        TextViewWindowHelper::clearSearchHighlights(this);
+    }
+}
+
+void MarkdownViewWindow::clearHighlights()
+{
+    if (isReadMode()) {
+        adapter()->findText(QStringList(), FindOption::FindNone);
+    } else {
+        TextViewWindowHelper::clearSearchHighlights(this);
     }
 }
 
diff --git a/src/widgets/markdownviewwindow.h b/src/widgets/markdownviewwindow.h
index 8b4d47f7..4bc84548 100644
--- a/src/widgets/markdownviewwindow.h
+++ b/src/widgets/markdownviewwindow.h
@@ -86,6 +86,8 @@ namespace vnotex
 
         void print() Q_DECL_OVERRIDE;
 
+        void clearHighlights() Q_DECL_OVERRIDE;
+
     protected:
         void syncEditorFromBuffer() Q_DECL_OVERRIDE;
 
diff --git a/src/widgets/textviewwindow.cpp b/src/widgets/textviewwindow.cpp
index 8e956c51..44ffda11 100644
--- a/src/widgets/textviewwindow.cpp
+++ b/src/widgets/textviewwindow.cpp
@@ -241,7 +241,7 @@ void TextViewWindow::handleReplaceAll(const QString &p_text, FindOptions p_optio
 
 void TextViewWindow::handleFindAndReplaceWidgetClosed()
 {
-    TextViewWindowHelper::handleFindAndReplaceWidgetClosed(this);
+    TextViewWindowHelper::clearSearchHighlights(this);
 }
 
 void TextViewWindow::updateEditorFromConfig()
@@ -317,3 +317,8 @@ void TextViewWindow::print()
         m_editor->getTextEdit()->print(printer.data());
     }
 }
+
+void TextViewWindow::clearHighlights()
+{
+    TextViewWindowHelper::clearSearchHighlights(this);
+}
diff --git a/src/widgets/textviewwindow.h b/src/widgets/textviewwindow.h
index be409f1c..52ebcfc4 100644
--- a/src/widgets/textviewwindow.h
+++ b/src/widgets/textviewwindow.h
@@ -70,6 +70,8 @@ namespace vnotex
 
         QPoint getFloatingWidgetPosition() Q_DECL_OVERRIDE;
 
+        void clearHighlights() Q_DECL_OVERRIDE;
+
     private:
         void setupUI();
 
diff --git a/src/widgets/textviewwindowhelper.h b/src/widgets/textviewwindowhelper.h
index c7e04e23..1e3e51a3 100644
--- a/src/widgets/textviewwindowhelper.h
+++ b/src/widgets/textviewwindowhelper.h
@@ -213,7 +213,7 @@ namespace vnotex
         }
 
         template <typename _ViewWindow>
-        static void handleFindAndReplaceWidgetClosed(_ViewWindow *p_win)
+        static void clearSearchHighlights(_ViewWindow *p_win)
         {
             p_win->m_editor->clearIncrementalSearchHighlight();
             p_win->m_editor->clearSearchHighlight();
diff --git a/src/widgets/viewarea.cpp b/src/widgets/viewarea.cpp
index b94b06bc..92eaf30f 100644
--- a/src/widgets/viewarea.cpp
+++ b/src/widgets/viewarea.cpp
@@ -67,6 +67,13 @@ ViewArea::ViewArea(QWidget *p_parent)
                     p_event->m_handled = true;
                 }
             });
+    connect(mainWindow, &MainWindow::minimizedToSystemTray,
+            this, [this]() {
+                if (ConfigMgr::getInst().getCoreConfig().isRecoverLastSessionOnStartEnabled()) {
+                    // Save it here, too. Avoid losing session when VNote is closed unexpectedly.
+                    saveSession();
+                }
+            });
 
     connect(mainWindow, &MainWindow::mainWindowClosedOnQuit,
             this, [this]() {
diff --git a/src/widgets/viewwindow.cpp b/src/widgets/viewwindow.cpp
index 363423b1..e2c8506a 100644
--- a/src/widgets/viewwindow.cpp
+++ b/src/widgets/viewwindow.cpp
@@ -1001,6 +1001,17 @@ void ViewWindow::setupShortcuts()
                     });
         }
     }
+
+    // ClearHighlights.
+    {
+        auto shortcut = WidgetUtils::createShortcut(editorConfig.getShortcut(EditorConfig::ClearHighlights), this, Qt::WidgetWithChildrenShortcut);
+        if (shortcut) {
+            connect(shortcut, &QShortcut::activated,
+                    this, [this]() {
+                        clearHighlights();
+                    });
+        }
+    }
 }
 
 void ViewWindow::wheelEvent(QWheelEvent *p_event)
@@ -1345,3 +1356,7 @@ void ViewWindow::print()
 {
     qWarning() << "print is not supported";
 }
+
+void ViewWindow::clearHighlights()
+{
+}
diff --git a/src/widgets/viewwindow.h b/src/widgets/viewwindow.h
index 14157031..da8e1f3d 100644
--- a/src/widgets/viewwindow.h
+++ b/src/widgets/viewwindow.h
@@ -256,6 +256,8 @@ namespace vnotex
 
         virtual void updateViewModeMenu(QMenu *p_menu);
 
+        virtual void clearHighlights();
+
         static QToolBar *createToolBar(QWidget *p_parent = nullptr);
 
         // The revision of the buffer of the last sync content.