diff --git a/libs/vtextedit b/libs/vtextedit
index 00b52913..58ad5d96 160000
--- a/libs/vtextedit
+++ b/libs/vtextedit
@@ -1 +1 @@
-Subproject commit 00b52913fe8f4ccf5ed5a0cbd3493b94fe354b25
+Subproject commit 58ad5d96359e2ab3f8f9255bd9194a0ebf1e6798
diff --git a/src/core/coreconfig.h b/src/core/coreconfig.h
index 46977f45..4ec556de 100644
--- a/src/core/coreconfig.h
+++ b/src/core/coreconfig.h
@@ -143,7 +143,7 @@ namespace vnotex
         int m_historyMaxCount = 100;
 
         // Whether store history in each notebook.
-        bool m_perNotebookHistoryEnabled = true;
+        bool m_perNotebookHistoryEnabled = false;
 
         static QStringList s_availableLocales;
     };
diff --git a/src/core/global.h b/src/core/global.h
index 74cc2b7d..50888941 100644
--- a/src/core/global.h
+++ b/src/core/global.h
@@ -94,8 +94,6 @@ namespace vnotex
     {
         Read,
         Edit,
-        FullPreview,
-        FocusPreview,
         Invalid
     };
 
diff --git a/src/core/mainconfig.cpp b/src/core/mainconfig.cpp
index bc13a770..93f94a5a 100644
--- a/src/core/mainconfig.cpp
+++ b/src/core/mainconfig.cpp
@@ -118,4 +118,5 @@ QString MainConfig::getVersion(const QJsonObject &p_jobj)
 void MainConfig::doVersionSpecificOverride()
 {
     // In a new version, we may want to change one value by force.
+    m_coreConfig->m_perNotebookHistoryEnabled = false;
 }
diff --git a/src/core/markdowneditorconfig.cpp b/src/core/markdowneditorconfig.cpp
index b52e4a24..ed11181d 100644
--- a/src/core/markdowneditorconfig.cpp
+++ b/src/core/markdowneditorconfig.cpp
@@ -73,6 +73,8 @@ void MarkdownEditorConfig::init(const QJsonObject &p_app, const QJsonObject &p_u
             m_inplacePreviewSources |= stringToInplacePreviewSource(src);
         }
     }
+
+    m_editViewMode = stringToEditViewMode(READSTR(QStringLiteral("edit_view_mode")));
 }
 
 QJsonObject MarkdownEditorConfig::toJson() const
@@ -122,6 +124,8 @@ QJsonObject MarkdownEditorConfig::toJson() const
         obj[QStringLiteral("inplace_preview_sources")] = srcs.join(QLatin1Char(';'));
     }
 
+    obj[QStringLiteral("edit_view_mode")] = editViewModeToString(m_editViewMode);
+
     return obj;
 }
 
@@ -519,3 +523,34 @@ void MarkdownEditorConfig::setInplacePreviewSources(InplacePreviewSources p_src)
 {
     updateConfig(m_inplacePreviewSources, p_src, this);
 }
+
+QString MarkdownEditorConfig::editViewModeToString(EditViewMode p_mode) const
+{
+    switch (p_mode) {
+    case EditViewMode::EditPreview:
+        return QStringLiteral("editpreview");
+
+    default:
+        return QStringLiteral("editonly");
+    }
+}
+
+MarkdownEditorConfig::EditViewMode MarkdownEditorConfig::stringToEditViewMode(const QString &p_str) const
+{
+    auto mode = p_str.toLower();
+    if (mode == QStringLiteral("editpreview")) {
+        return EditViewMode::EditPreview;
+    } else {
+        return EditViewMode::EditOnly;
+    }
+}
+
+MarkdownEditorConfig::EditViewMode MarkdownEditorConfig::getEditViewMode() const
+{
+    return m_editViewMode;
+}
+
+void MarkdownEditorConfig::setEditViewMode(EditViewMode p_mode)
+{
+    updateConfig(m_editViewMode, p_mode, this);
+}
diff --git a/src/core/markdowneditorconfig.h b/src/core/markdowneditorconfig.h
index 025fc19f..84ca9c7a 100644
--- a/src/core/markdowneditorconfig.h
+++ b/src/core/markdowneditorconfig.h
@@ -39,6 +39,12 @@ namespace vnotex
         };
         Q_DECLARE_FLAGS(InplacePreviewSources, InplacePreviewSource);
 
+        enum EditViewMode
+        {
+            EditOnly,
+            EditPreview
+        };
+
         MarkdownEditorConfig(ConfigMgr *p_mgr,
                              IConfig *p_topConfig,
                              const QSharedPointer<TextEditorConfig> &p_textEditorConfig);
@@ -130,6 +136,9 @@ namespace vnotex
         InplacePreviewSources getInplacePreviewSources() const;
         void setInplacePreviewSources(InplacePreviewSources p_src);
 
+        EditViewMode getEditViewMode() const;
+        void setEditViewMode(EditViewMode p_mode);
+
     private:
         friend class MainConfig;
 
@@ -148,6 +157,9 @@ namespace vnotex
         QString inplacePreviewSourceToString(InplacePreviewSource p_src) const;
         InplacePreviewSource stringToInplacePreviewSource(const QString &p_str) const;
 
+        QString editViewModeToString(EditViewMode p_mode) const;
+        EditViewMode stringToEditViewMode(const QString &p_str) const;
+
         QSharedPointer<TextEditorConfig> m_textEditorConfig;
 
         WebResource m_viewerResource;
@@ -227,6 +239,9 @@ namespace vnotex
         QString m_editorOverriddenFontFamily;
 
         InplacePreviewSources m_inplacePreviewSources = InplacePreviewSource::NoInplacePreview;
+
+        // View mode in edit mode.
+        EditViewMode m_editViewMode = EditViewMode::EditOnly;
     };
 }
 
diff --git a/src/core/notebookconfigmgr/vxnotebookconfigmgr.cpp b/src/core/notebookconfigmgr/vxnotebookconfigmgr.cpp
index 30bb9c16..c94f1687 100644
--- a/src/core/notebookconfigmgr/vxnotebookconfigmgr.cpp
+++ b/src/core/notebookconfigmgr/vxnotebookconfigmgr.cpp
@@ -826,7 +826,9 @@ bool VXNotebookConfigMgr::isBuiltInFolder(const Node *p_node, const QString &p_n
     if (name == nb->getImageFolder().toLower()
         || name == nb->getAttachmentFolder().toLower()
         || name == QStringLiteral("_v_images")
-        || name == QStringLiteral("_v_attachments")) {
+        || name == QStringLiteral("_v_attachments")
+        || name == QStringLiteral("vx_images")
+        || name == QStringLiteral("vx_attachments")) {
         return true;
     }
     return BundleNotebookConfigMgr::isBuiltInFolder(p_node, p_name);
diff --git a/src/data/core/core.qrc b/src/data/core/core.qrc
index 17dcb9bf..2bfdf372 100644
--- a/src/data/core/core.qrc
+++ b/src/data/core/core.qrc
@@ -13,6 +13,7 @@
         <file>icons/discard_editor.svg</file>
         <file>icons/edit_editor.svg</file>
         <file>icons/read_editor.svg</file>
+        <file>icons/view_mode_editor.svg</file>
         <file>icons/expand.svg</file>
         <file>icons/fullscreen.svg</file>
         <file>icons/tag_dock.svg</file>
diff --git a/src/data/core/icons/view_mode_editor.svg b/src/data/core/icons/view_mode_editor.svg
new file mode 100644
index 00000000..f2cc25ab
--- /dev/null
+++ b/src/data/core/icons/view_mode_editor.svg
@@ -0,0 +1 @@
+<?xml version="1.0" standalone="no"?><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd"><svg t="1636336824519" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="2399" width="512" height="512" xmlns:xlink="http://www.w3.org/1999/xlink"><defs><style type="text/css"></style></defs><path d="M896 809.984l0-553.984-384 0 0 553.984 384 0zM896 169.984q34.005333 0 59.989333 25.984t25.984 59.989333l0 553.984q0 34.005333-25.984 59.989333t-59.989333 25.984l-768 0q-34.005333 0-59.989333-25.984t-25.984-59.989333l0-553.984q0-34.005333 25.984-59.989333t59.989333-25.984l768 0zM553.984 617.984l299.989333 0 0 64-299.989333 0 0-64zM553.984 406.016l299.989333 0 0 64-299.989333 0 0-64zM553.984 512l299.989333 0 0 64-299.989333 0 0-64z" p-id="2400" fill="#000000"></path></svg>
\ No newline at end of file
diff --git a/src/data/core/translations/vnote_zh_CN.ts b/src/data/core/translations/vnote_zh_CN.ts
index 3a751098..a7453dee 100644
--- a/src/data/core/translations/vnote_zh_CN.ts
+++ b/src/data/core/translations/vnote_zh_CN.ts
@@ -4821,7 +4821,7 @@ Description: %3</source>
     <message>
         <location filename="../../../widgets/dialogs/settings/texteditorpage.cpp" line="57"/>
         <source>Normal</source>
-        <translation>正常</translation>
+        <translation>普通</translation>
     </message>
     <message>
         <location filename="../../../widgets/dialogs/settings/texteditorpage.cpp" line="58"/>
diff --git a/src/data/core/vnotex.json b/src/data/core/vnotex.json
index 87322ba9..6c1637bc 100644
--- a/src/data/core/vnotex.json
+++ b/src/data/core/vnotex.json
@@ -76,7 +76,7 @@
         "check_for_updates_on_start" : true,
         "//comment" : "Max count of the history items for each notebook and session config",
         "history_max_count" : 100,
-        "per_notebook_history" : true
+        "per_notebook_history" : false
     },
     "editor" : {
         "core": {
@@ -357,7 +357,9 @@
             "editor_overridden_font_family" : "",
             "//comment" : "Sources to enable inplace preview, separated by ;",
             "//comment" : "imagelink/codeblock/math",
-            "inplace_preview_sources" : "imagelink;codeblock;math"
+            "inplace_preview_sources" : "imagelink;codeblock;math",
+            "//comment" : "view mode of edit mode: editonly/editpreview",
+            "edit_view_mode" : "editonly"
         },
         "image_host" : {
             "hosts" : [
diff --git a/src/utils/widgetutils.cpp b/src/utils/widgetutils.cpp
index de1ca843..9ea4a6bb 100644
--- a/src/utils/widgetutils.cpp
+++ b/src/utils/widgetutils.cpp
@@ -24,6 +24,7 @@
 #include <QLineEdit>
 #include <QLayout>
 #include <QPushButton>
+#include <QSplitter>
 
 #include <core/global.h>
 
@@ -418,3 +419,42 @@ void WidgetUtils::setContentsMargins(QLayout *p_layout)
     // Use 0 bottom margin to align dock widgets with the content area.
     p_layout->setContentsMargins(CONTENTS_MARGIN, CONTENTS_MARGIN, CONTENTS_MARGIN, 0);
 }
+
+bool WidgetUtils::distributeWidgetsOfSplitter(QSplitter *p_splitter)
+{
+    if (!p_splitter) {
+        return false;
+    }
+
+    if (p_splitter->count() == 0) {
+        return false;
+    } else if (p_splitter->count() == 1) {
+        return true;
+    }
+
+    auto sizes = p_splitter->sizes();
+    int totalWidth = 0;
+    for (auto sz : sizes) {
+        totalWidth += sz;
+    }
+
+    int newWidth = totalWidth / sizes.size();
+    if (newWidth == 0) {
+        return false;
+    }
+
+    bool changed = false;
+    for (int i = 0; i < sizes.size(); ++i) {
+        if (sizes[i] != newWidth) {
+            sizes[i] = newWidth;
+            changed = true;
+        }
+    }
+
+    if (changed) {
+        p_splitter->setSizes(sizes);
+        return true;
+    }
+
+    return false;
+}
diff --git a/src/utils/widgetutils.h b/src/utils/widgetutils.h
index 9329e08a..797c141a 100644
--- a/src/utils/widgetutils.h
+++ b/src/utils/widgetutils.h
@@ -20,6 +20,7 @@ class QShortcut;
 class QLineEdit;
 class QLayout;
 class QPushButton;
+class QSplitter;
 
 namespace vnotex
 {
@@ -86,6 +87,8 @@ namespace vnotex
 
         static void setContentsMargins(QLayout *p_layout);
 
+        static bool distributeWidgetsOfSplitter(QSplitter *p_splitter);
+
     private:
         static void resizeToHideScrollBar(QScrollArea *p_scroll, bool p_vertical, bool p_horizontal);
     };
diff --git a/src/widgets/dialogs/managenotebooksdialog.cpp b/src/widgets/dialogs/managenotebooksdialog.cpp
index 37b10ae2..ad1beb13 100644
--- a/src/widgets/dialogs/managenotebooksdialog.cpp
+++ b/src/widgets/dialogs/managenotebooksdialog.cpp
@@ -251,10 +251,10 @@ bool ManageNotebooksDialog::saveChangesToNotebook()
     return true;
 }
 
-void ManageNotebooksDialog::closeNotebook(const Notebook *p_notebook)
+bool ManageNotebooksDialog::closeNotebook(const Notebook *p_notebook)
 {
     if (!p_notebook) {
-        return;
+        return false;
     }
 
     int ret = MessageBoxHelper::questionOkCancel(MessageBoxHelper::Question,
@@ -264,7 +264,7 @@ void ManageNotebooksDialog::closeNotebook(const Notebook *p_notebook)
                                                  tr("Notebook location: %1").arg(p_notebook->getRootFolderAbsolutePath()),
                                                  this);
     if (ret != QMessageBox::Ok) {
-        return;
+        return false;
     }
 
     try
@@ -274,11 +274,10 @@ void ManageNotebooksDialog::closeNotebook(const Notebook *p_notebook)
         MessageBoxHelper::notify(MessageBoxHelper::Warning,
                                  tr("Failed to close notebook (%1)").arg(p_e.what()),
                                  this);
-        loadNotebooks(nullptr);
-        return;
     }
 
     loadNotebooks(nullptr);
+    return true;
 }
 
 void ManageNotebooksDialog::removeNotebook(const Notebook *p_notebook)
@@ -298,9 +297,9 @@ void ManageNotebooksDialog::removeNotebook(const Notebook *p_notebook)
 
     const auto rootFolder = p_notebook->getRootFolderAbsolutePath();
 
-    closeNotebook(p_notebook);
-
-    WidgetUtils::openUrlByDesktop(QUrl::fromLocalFile(rootFolder));
+    if (closeNotebook(p_notebook)) {
+        WidgetUtils::openUrlByDesktop(QUrl::fromLocalFile(rootFolder));
+    }
 }
 
 bool ManageNotebooksDialog::checkUnsavedChanges()
diff --git a/src/widgets/dialogs/managenotebooksdialog.h b/src/widgets/dialogs/managenotebooksdialog.h
index d3eda054..60b9a7d5 100644
--- a/src/widgets/dialogs/managenotebooksdialog.h
+++ b/src/widgets/dialogs/managenotebooksdialog.h
@@ -45,7 +45,7 @@ namespace vnotex
 
         Notebook *getNotebookFromItem(const QListWidgetItem *p_item) const;
 
-        void closeNotebook(const Notebook *p_notebook);
+        bool closeNotebook(const Notebook *p_notebook);
 
         void removeNotebook(const Notebook *p_notebook);
 
diff --git a/src/widgets/editors/markdownvieweradapter.cpp b/src/widgets/editors/markdownvieweradapter.cpp
index f17c8fbc..a0855b7d 100644
--- a/src/widgets/editors/markdownvieweradapter.cpp
+++ b/src/widgets/editors/markdownvieweradapter.cpp
@@ -74,7 +74,7 @@ void MarkdownViewerAdapter::setText(int p_revision,
                                     const QString &p_text,
                                     int p_lineNumber)
 {
-    if (p_revision == m_revision) {
+    if (p_revision == m_revision && p_revision != 0) {
         // Only sync line number position.
         scrollToPosition(Position(p_lineNumber, ""));
         return;
@@ -92,16 +92,9 @@ void MarkdownViewerAdapter::setText(int p_revision,
     }
 }
 
-void MarkdownViewerAdapter::setText(const QString &p_text)
+void MarkdownViewerAdapter::setText(const QString &p_text, int p_lineNumber)
 {
-    m_revision = 0;
-    if (m_viewerReady) {
-        emit textUpdated(p_text);
-    } else {
-        m_pendingActions.append([this, p_text]() {
-            emit textUpdated(p_text);
-        });
-    }
+    setText(0, p_text, p_lineNumber);
 }
 
 void MarkdownViewerAdapter::setReady(bool p_ready)
diff --git a/src/widgets/editors/markdownvieweradapter.h b/src/widgets/editors/markdownvieweradapter.h
index 23461513..531c8b3e 100644
--- a/src/widgets/editors/markdownvieweradapter.h
+++ b/src/widgets/editors/markdownvieweradapter.h
@@ -87,7 +87,8 @@ namespace vnotex
                      const QString &p_text,
                      int p_lineNumber);
 
-        void setText(const QString &p_text);
+        // @p_lineNumber: the line number needed to sync, -1 for invalid.
+        void setText(const QString &p_text, int p_lineNumber = -1);
 
         void scrollToPosition(const Position &p_pos);
 
diff --git a/src/widgets/mainwindow.cpp b/src/widgets/mainwindow.cpp
index c2d23428..f6f08381 100644
--- a/src/widgets/mainwindow.cpp
+++ b/src/widgets/mainwindow.cpp
@@ -525,11 +525,10 @@ void MainWindow::focusViewArea()
 void MainWindow::setupToolBar()
 {
     const int sz = ConfigMgr::getInst().getCoreConfig().getToolBarIconSize();
-    const QSize iconSize(sz, sz);
 
     if (isFrameless()) {
         auto toolBar = new TitleToolBar(tr("Global"), this);
-        toolBar->setIconSize(iconSize);
+        toolBar->setIconSize(QSize(sz + 4, sz + 4));
         ToolBarHelper::setupToolBars(this, toolBar);
         toolBar->addTitleBarIcons(ToolBarHelper::generateIcon(QStringLiteral("minimize.svg")),
                                   ToolBarHelper::generateIcon(QStringLiteral("maximize.svg")),
@@ -540,7 +539,7 @@ void MainWindow::setupToolBar()
                 toolBar, &TitleToolBar::updateMaximizeAct);
     } else {
         auto toolBar = new QToolBar(tr("Global"), this);
-        toolBar->setIconSize(iconSize);
+        toolBar->setIconSize(QSize(sz, sz));
         ToolBarHelper::setupToolBars(this, toolBar);
     }
 
diff --git a/src/widgets/markdownviewwindow.cpp b/src/widgets/markdownviewwindow.cpp
index fca0eefb..a9287163 100644
--- a/src/widgets/markdownviewwindow.cpp
+++ b/src/widgets/markdownviewwindow.cpp
@@ -9,15 +9,17 @@
 #include <QLabel>
 #include <QApplication>
 #include <QProgressDialog>
+#include <QMenu>
+#include <QActionGroup>
 
 #include <core/fileopenparameters.h>
 #include <core/editorconfig.h>
-#include <core/markdowneditorconfig.h>
 #include <core/htmltemplatehelper.h>
 #include <vtextedit/vtextedit.h>
 #include <vtextedit/pegmarkdownhighlighter.h>
 #include <vtextedit/markdowneditorconfig.h>
 #include <utils/pathutils.h>
+#include <utils/widgetutils.h>
 #include <buffer/markdownbuffer.h>
 #include <core/vnotex.h>
 #include <core/thememgr.h>
@@ -130,7 +132,6 @@ void MarkdownViewWindow::setModeInternal(ViewWindowMode p_mode, bool p_syncBuffe
             toggleDebug();
         }
 
-        bool hideViewer = m_viewerReady;
         if (!m_editor) {
             // We need viewer to preview.
             if (!m_viewer) {
@@ -139,7 +140,6 @@ void MarkdownViewWindow::setModeInternal(ViewWindowMode p_mode, bool p_syncBuffe
                 // Must show the viewer to let it init with the correct DPI.
                 // Will hide it when viewerReady().
                 m_viewer->show();
-                hideViewer = false;
             }
 
             setupTextEditor();
@@ -153,10 +153,7 @@ void MarkdownViewWindow::setModeInternal(ViewWindowMode p_mode, bool p_syncBuffe
         m_editor->show();
         m_editor->setFocus();
 
-        if (hideViewer) {
-            Q_ASSERT(m_viewer);
-            m_viewer->hide();
-        }
+        setEditViewMode(m_editViewMode);
 
         getMainStatusWidget()->setCurrentWidget(m_textEditorStatusWidget.get());
         break;
@@ -167,7 +164,7 @@ void MarkdownViewWindow::setModeInternal(ViewWindowMode p_mode, bool p_syncBuffe
         break;
     }
 
-    // Let editor to show or scrollToLine will not work correctly.
+    // Let editor to show, or scrollToLine will not work correctly.
     QCoreApplication::processEvents();
 
     if (p_syncBuffer) {
@@ -267,6 +264,7 @@ void MarkdownViewWindow::setupToolBar()
 
     addAction(toolBar, ViewWindowToolBarHelper::EditReadDiscard);
     addAction(toolBar, ViewWindowToolBarHelper::Save);
+    addAction(toolBar, ViewWindowToolBarHelper::ViewMode);
 
     toolBar->addSeparator();
 
@@ -336,10 +334,13 @@ void MarkdownViewWindow::setupTextEditor()
 
     updateConfigRevision();
 
+    m_editViewMode = markdownEditorConfig.getEditViewMode();
+
     m_editor = new MarkdownEditor(markdownEditorConfig,
                                   createMarkdownEditorConfig(editorConfig, markdownEditorConfig),
                                   createMarkdownEditorParameters(editorConfig, markdownEditorConfig),
                                   this);
+    // Always editor comes first.
     m_splitter->insertWidget(0, m_editor);
 
     TextViewWindowHelper::connectEditor(this);
@@ -486,8 +487,9 @@ void MarkdownViewWindow::setupViewer()
     connect(adapter, &MarkdownViewerAdapter::viewerReady,
             this, [this]() {
                 m_viewerReady = true;
+
                 if (m_mode == ViewWindowMode::Edit) {
-                    m_viewer->hide();
+                    setEditViewMode(m_editViewMode);
                 }
             });
 }
@@ -623,7 +625,7 @@ EditorMarkdownViewerAdapter *MarkdownViewWindow::adapter() const
 
 int MarkdownViewWindow::getEditLineNumber() const
 {
-    if (m_previousMode == ViewWindowMode::Edit || m_previousMode == ViewWindowMode::FocusPreview) {
+    if (m_previousMode == ViewWindowMode::Edit) {
         if (m_editor) {
             return m_editor->getTopLine();
         }
@@ -1153,10 +1155,6 @@ QString MarkdownViewWindow::selectedText() const
         return m_viewer->selectedText();
 
     case ViewWindowMode::Edit:
-        Q_FALLTHROUGH();
-    case ViewWindowMode::FullPreview:
-        Q_FALLTHROUGH();
-    case ViewWindowMode::FocusPreview:
         Q_ASSERT(m_editor);
         return m_editor->getTextEdit()->selectedText();
 
@@ -1250,3 +1248,111 @@ void MarkdownViewWindow::setupDebugViewer()
     m_debugViewer->resize(m_splitter->width(), m_splitter->height() / 2);
     mainSplitter->addWidget(m_debugViewer);
 }
+
+void MarkdownViewWindow::updateViewModeMenu(QMenu *p_menu)
+{
+    p_menu->clear();
+
+    if (isReadMode()) {
+        auto act = p_menu->addAction(tr("View Mode Not Supported In Read Mode"));
+        act->setEnabled(false);
+        return;
+    }
+
+    if (!m_viewModeActionGroup) {
+        m_viewModeActionGroup = new QActionGroup(this);
+        connect(m_viewModeActionGroup, &QActionGroup::triggered,
+                this, [this](QAction *act) {
+                    auto mode = static_cast<MarkdownEditorConfig::EditViewMode>(act->data().toInt());
+                    if (mode != m_editViewMode) {
+                        ConfigMgr::getInst().getEditorConfig().getMarkdownEditorConfig().setEditViewMode(mode);
+                        setEditViewMode(mode);
+                    }
+                });
+    }
+
+    {
+        auto act = p_menu->addAction(tr("Edit Only"));
+        act->setCheckable(true);
+        act->setData(static_cast<int>(MarkdownEditorConfig::EditViewMode::EditOnly));
+        m_viewModeActionGroup->addAction(act);
+
+        if (act->data().toInt() == m_editViewMode) {
+            act->setChecked(true);
+        }
+    }
+
+    {
+        auto act = p_menu->addAction(tr("Edit with Preview"));
+        act->setCheckable(true);
+        act->setData(static_cast<int>(MarkdownEditorConfig::EditViewMode::EditPreview));
+        m_viewModeActionGroup->addAction(act);
+
+        if (act->data().toInt() == m_editViewMode) {
+            act->setChecked(true);
+        }
+    }
+}
+
+void MarkdownViewWindow::setEditViewMode(MarkdownEditorConfig::EditViewMode p_mode)
+{
+    Q_ASSERT(m_mode == ViewWindowMode::Edit);
+
+    m_editViewMode = p_mode;
+
+    switch (p_mode) {
+    case MarkdownEditorConfig::EditViewMode::EditOnly:
+    {
+        if (m_viewerReady) {
+            m_viewer->hide();
+        }
+
+        disconnect(m_editor->getTextEdit(), &vte::VTextEdit::contentsChanged,
+                   this, &MarkdownViewWindow::syncEditorContentsToPreview);
+        disconnect(m_editor, &MarkdownEditor::topLineChanged,
+                   this, &MarkdownViewWindow::syncEditorPositionToPreview);
+        break;
+    }
+
+    case MarkdownEditorConfig::EditViewMode::EditPreview:
+    {
+        m_viewer->show();
+        WidgetUtils::distributeWidgetsOfSplitter(m_splitter);
+
+        if (m_viewerReady) {
+            connect(m_editor->getTextEdit(), &vte::VTextEdit::contentsChanged,
+                    this, &MarkdownViewWindow::syncEditorContentsToPreview,
+                    Qt::UniqueConnection);
+            connect(m_editor, &MarkdownEditor::topLineChanged,
+                    this, &MarkdownViewWindow::syncEditorPositionToPreview,
+                    Qt::UniqueConnection);
+
+            syncEditorContentsToPreview();
+        }
+
+        break;
+    }
+
+    default:
+        Q_ASSERT(false);
+        break;
+    }
+}
+
+void MarkdownViewWindow::syncEditorContentsToPreview()
+{
+    if (isReadMode() || m_editViewMode == MarkdownEditorConfig::EditViewMode::EditOnly) {
+        return;
+    }
+
+    adapter()->setText(m_editor->getText(), m_editor->getTopLine());
+}
+
+void MarkdownViewWindow::syncEditorPositionToPreview()
+{
+    if (isReadMode() || m_editViewMode == MarkdownEditorConfig::EditViewMode::EditOnly) {
+        return;
+    }
+
+    adapter()->scrollToPosition(MarkdownViewerAdapter::Position(m_editor->getTopLine(), QString()));
+}
diff --git a/src/widgets/markdownviewwindow.h b/src/widgets/markdownviewwindow.h
index 4ca8cd81..b832147f 100644
--- a/src/widgets/markdownviewwindow.h
+++ b/src/widgets/markdownviewwindow.h
@@ -5,9 +5,12 @@
 
 #include <QScopedPointer>
 
+#include <core/markdowneditorconfig.h>
+
 class QSplitter;
 class QStackedWidget;
 class QWebEngineView;
+class QActionGroup;
 
 namespace vte
 {
@@ -22,7 +25,6 @@ namespace vnotex
     class EditorMarkdownViewerAdapter;
     class PreviewHelper;
     struct Outline;
-    class MarkdownEditorConfig;
     class EditorConfig;
     class ImageHost;
     class SearchToken;
@@ -98,6 +100,8 @@ namespace vnotex
 
         QString selectedText() const Q_DECL_OVERRIDE;
 
+        void updateViewModeMenu(QMenu *p_menu) Q_DECL_OVERRIDE;
+
     private:
         void setupUI();
 
@@ -164,6 +168,12 @@ namespace vnotex
 
         void setupDebugViewer();
 
+        void setEditViewMode(MarkdownEditorConfig::EditViewMode p_mode);
+
+        void syncEditorContentsToPreview();
+
+        void syncEditorPositionToPreview();
+
         template <class T>
         static QSharedPointer<Outline> headingsToOutline(const QVector<T> &p_headings);
 
@@ -210,6 +220,10 @@ namespace vnotex
         ImageHost *m_imageHost = nullptr;
 
         bool m_viewerReady = false;
+
+        QActionGroup *m_viewModeActionGroup = nullptr;
+
+        MarkdownEditorConfig::EditViewMode m_editViewMode = MarkdownEditorConfig::EditViewMode::EditOnly;
     };
 }
 
diff --git a/src/widgets/viewarea.cpp b/src/widgets/viewarea.cpp
index 505ae145..b94b06bc 100644
--- a/src/widgets/viewarea.cpp
+++ b/src/widgets/viewarea.cpp
@@ -596,30 +596,10 @@ QSplitter *ViewArea::tryGetParentSplitter(const QWidget *p_widget) const
 
 void ViewArea::distributeViewSplitsOfSplitter(QSplitter *p_splitter)
 {
-    if (!p_splitter || p_splitter->count() <= 1) {
+    if (!WidgetUtils::distributeWidgetsOfSplitter(p_splitter)) {
         return;
     }
 
-    // Distribute the direct children of splitter.
-    {
-        auto sizes = p_splitter->sizes();
-        int totalWidth = 0;
-        for (auto sz : sizes) {
-            totalWidth += sz;
-        }
-
-        int newWidth = totalWidth / sizes.size();
-        if (newWidth <= 0) {
-            return;
-        }
-
-        for (int i = 0; i < sizes.size(); ++i) {
-            sizes[i] = newWidth;
-        }
-
-        p_splitter->setSizes(sizes);
-    }
-
     // Distribute child splitter.
     for (int i = 0; i < p_splitter->count(); ++i) {
         auto childSplitter = dynamic_cast<QSplitter *>(p_splitter->widget(i));
diff --git a/src/widgets/viewwindow.cpp b/src/widgets/viewwindow.cpp
index eb79c2f4..2396b407 100644
--- a/src/widgets/viewwindow.cpp
+++ b/src/widgets/viewwindow.cpp
@@ -37,6 +37,7 @@
 #include "editors/statuswidget.h"
 #include "propertydefs.h"
 #include "floatingwidget.h"
+#include "widgetsfactory.h"
 
 using namespace vnotex;
 
@@ -341,6 +342,25 @@ QAction *ViewWindow::addAction(QToolBar *p_toolBar, ViewWindowToolBarHelper::Act
         break;
     }
 
+    case ViewWindowToolBarHelper::ViewMode:
+    {
+        act = ViewWindowToolBarHelper::addAction(p_toolBar, p_action);
+        connect(this, &ViewWindow::bufferChanged,
+                this, [this, act]() {
+                    act->setEnabled(getBuffer());
+                });
+
+        auto toolBtn = dynamic_cast<QToolButton *>(p_toolBar->widgetForAction(act));
+        Q_ASSERT(toolBtn);
+        auto menu = WidgetsFactory::createMenu(p_toolBar);
+        toolBtn->setMenu(menu);
+        connect(menu, &QMenu::aboutToShow,
+                this, [this, menu]() {
+                    updateViewModeMenu(menu);
+                });
+        break;
+    }
+
     case ViewWindowToolBarHelper::TypeHeading:
     {
         act = ViewWindowToolBarHelper::addAction(p_toolBar, p_action);
@@ -675,7 +695,7 @@ void ViewWindow::discardChangesAndRead()
 
 bool ViewWindow::inModeCanInsert() const
 {
-    return m_mode == ViewWindowMode::Edit || m_mode == ViewWindowMode::FocusPreview || m_mode == ViewWindowMode::FullPreview;
+    return m_mode == ViewWindowMode::Edit;
 }
 
 void ViewWindow::handleTypeAction(TypeAction p_action)
@@ -1300,3 +1320,11 @@ void ViewWindow::toggleDebug()
 {
     qDebug() << "debug is not supported";
 }
+
+void ViewWindow::updateViewModeMenu(QMenu *p_menu)
+{
+    p_menu->clear();
+
+    auto act = p_menu->addAction(tr("View Mode Not Supported"));
+    act->setEnabled(false);
+}
diff --git a/src/widgets/viewwindow.h b/src/widgets/viewwindow.h
index a391c19b..32fe2188 100644
--- a/src/widgets/viewwindow.h
+++ b/src/widgets/viewwindow.h
@@ -252,6 +252,8 @@ namespace vnotex
 
         virtual QPoint getFloatingWidgetPosition();
 
+        virtual void updateViewModeMenu(QMenu *p_menu);
+
         static QToolBar *createToolBar(QWidget *p_parent = nullptr);
 
         // The revision of the buffer of the last sync content.
diff --git a/src/widgets/viewwindowtoolbarhelper.cpp b/src/widgets/viewwindowtoolbarhelper.cpp
index 6319f957..b1eeecee 100644
--- a/src/widgets/viewwindowtoolbarhelper.cpp
+++ b/src/widgets/viewwindowtoolbarhelper.cpp
@@ -118,6 +118,18 @@ QAction *ViewWindowToolBarHelper::addAction(QToolBar *p_tb, Action p_action)
         break;
     }
 
+    case Action::ViewMode:
+    {
+        act = p_tb->addAction(ToolBarHelper::generateIcon("view_mode_editor.svg"),
+                              ViewWindow::tr("View Mode"));
+
+        auto toolBtn = dynamic_cast<QToolButton *>(p_tb->widgetForAction(act));
+        Q_ASSERT(toolBtn);
+        toolBtn->setPopupMode(QToolButton::InstantPopup);
+        toolBtn->setProperty(PropertyDefs::c_toolButtonWithoutMenuIndicator, true);
+        break;
+    }
+
     case Action::TypeHeading:
     {
         act = p_tb->addAction(ToolBarHelper::generateIcon("type_heading_editor.svg"),
diff --git a/src/widgets/viewwindowtoolbarhelper.h b/src/widgets/viewwindowtoolbarhelper.h
index 108eefbe..e91ab546 100644
--- a/src/widgets/viewwindowtoolbarhelper.h
+++ b/src/widgets/viewwindowtoolbarhelper.h
@@ -17,6 +17,7 @@ namespace vnotex
         {
             Save,
             EditReadDiscard,
+            ViewMode,
 
             // Make sure they are put together.
             // Including Heading1-6 and HeadingNone.