diff --git a/PdfForQtLib/PdfForQtLib.pro b/PdfForQtLib/PdfForQtLib.pro
index 5beb429..e22c314 100644
--- a/PdfForQtLib/PdfForQtLib.pro
+++ b/PdfForQtLib/PdfForQtLib.pro
@@ -36,6 +36,7 @@ DEFINES += QT_DEPRECATED_WARNINGS
 DESTDIR = $$OUT_PWD/..
 
 SOURCES += \
+    sources/pdfitemmodels.cpp \
     sources/pdfobject.cpp \
     sources/pdfoptionalcontent.cpp \
     sources/pdfparser.cpp \
@@ -61,6 +62,7 @@ SOURCES += \
     sources/pdfimage.cpp
 
 HEADERS += \
+    sources/pdfitemmodels.h \
     sources/pdfobject.h \
     sources/pdfoptionalcontent.h \
     sources/pdfparser.h \
diff --git a/PdfForQtLib/sources/pdfitemmodels.cpp b/PdfForQtLib/sources/pdfitemmodels.cpp
new file mode 100644
index 0000000..513ec94
--- /dev/null
+++ b/PdfForQtLib/sources/pdfitemmodels.cpp
@@ -0,0 +1,275 @@
+//    Copyright (C) 2019 Jakub Melka
+//
+//    This file is part of PdfForQt.
+//
+//    PdfForQt is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Lesser General Public License as published by
+//    the Free Software Foundation, either version 3 of the License, or
+//    (at your option) any later version.
+//
+//    PdfForQt is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//    GNU Lesser General Public License for more details.
+//
+//    You should have received a copy of the GNU Lesser General Public License
+//    along with PDFForQt.  If not, see <https://www.gnu.org/licenses/>.
+
+#include "pdfitemmodels.h"
+#include "pdfdocument.h"
+
+namespace pdf
+{
+
+PDFTreeItem::~PDFTreeItem()
+{
+    qDeleteAll(m_children);
+}
+
+PDFTreeItemModel::PDFTreeItemModel(QObject* parent) :
+    QAbstractItemModel(parent),
+    m_document(nullptr)
+{
+
+}
+
+void PDFTreeItemModel::setDocument(const PDFDocument* document)
+{
+    if (m_document != document)
+    {
+        m_document = document;
+        update();
+    }
+}
+
+bool PDFTreeItemModel::isEmpty() const
+{
+    return rowCount(QModelIndex()) == 0;
+}
+
+QModelIndex PDFTreeItemModel::index(int row, int column, const QModelIndex& parent) const
+{
+    if (hasIndex(row, column, parent))
+    {
+        const PDFTreeItem* parentItem = nullptr;
+
+        if (!parent.isValid())
+        {
+            parentItem = m_rootItem.get();
+        }
+        else
+        {
+            parentItem = static_cast<PDFTreeItem*>(parent.internalPointer());
+        }
+
+        return createIndex(row, column, const_cast<PDFTreeItem*>(parentItem->getChild(row)));
+    }
+
+    return QModelIndex();
+}
+
+QModelIndex PDFTreeItemModel::parent(const QModelIndex& child) const
+{
+    if (child.isValid())
+    {
+        const PDFTreeItem* childItem = static_cast<PDFTreeItem*>(child.internalPointer());
+        const PDFTreeItem* parentItem = childItem->getParent();
+
+        if (parentItem != m_rootItem.get())
+        {
+            return createIndex(parentItem->getRow(), child.column(), const_cast<PDFTreeItem*>(parentItem));
+        }
+    }
+
+    return QModelIndex();
+}
+
+int PDFTreeItemModel::rowCount(const QModelIndex& parent) const
+{
+    if (parent.isValid())
+    {
+        const PDFTreeItem* parentItem = static_cast<PDFTreeItem*>(parent.internalPointer());
+        return parentItem->getChildCount();
+    }
+
+    return m_rootItem ? m_rootItem->getChildCount() : 0;
+}
+
+bool PDFTreeItemModel::hasChildren(const QModelIndex& parent) const
+{
+    return rowCount(parent) > 0;
+}
+
+Qt::ItemFlags PDFTreeItemModel::flags(const QModelIndex& index) const
+{
+    if (!index.isValid())
+    {
+        return Qt::NoItemFlags;
+    }
+
+    return QAbstractItemModel::flags(index);
+}
+
+
+int PDFOptionalContentTreeItemModel::columnCount(const QModelIndex& parent) const
+{
+    Q_UNUSED(parent);
+    return 1;
+}
+
+QVariant PDFOptionalContentTreeItemModel::data(const QModelIndex& index, int role) const
+{
+    if (!index.isValid())
+    {
+        return QVariant();
+    }
+
+    const PDFOptionalContentTreeItem* item = static_cast<const PDFOptionalContentTreeItem*>(index.internalPointer());
+    switch (role)
+    {
+        case Qt::DisplayRole:
+            return item->getText();
+
+        case Qt::CheckStateRole:
+            return Qt::Checked;
+
+        default:
+            break;
+    }
+
+    return QVariant();
+}
+
+void PDFOptionalContentTreeItemModel::update()
+{
+    beginResetModel();
+
+    PDFOptionalContentTreeItem* root = new PDFOptionalContentTreeItem(nullptr, PDFObjectReference(), QString(), false);
+    m_rootItem.reset(root);
+
+    if (m_document)
+    {
+        const PDFOptionalContentProperties* optionalContentProperties = m_document->getCatalog()->getOptionalContentProperties();
+        if (optionalContentProperties->isValid())
+        {
+            const PDFOptionalContentConfiguration& configuration = optionalContentProperties->getDefaultConfiguration();
+            const PDFObject& orderObject = m_document->getObject(configuration.getOrder());
+            const std::vector<PDFObjectReference>& ocgs = optionalContentProperties->getAllOptionalContentGroups();
+            const std::vector<PDFObjectReference>& locked = configuration.getLocked();
+
+            // We must detect cycles in the reference array
+            std::set<PDFObjectReference> lockedOptionalContentGroups(locked.cbegin(), locked.cend());
+            std::set<PDFObjectReference> optionalContentGroups(ocgs.cbegin(), ocgs.cend());
+            std::set<PDFObjectReference> processedReferences;
+
+            PDFDocumentDataLoaderDecorator loader(m_document);
+            std::function<PDFOptionalContentTreeItem*(const PDFObject&)> processObject = [&, this](const PDFObject& object) -> PDFOptionalContentTreeItem*
+            {
+                PDFObject dereferencedObject = object;
+                if (object.isReference())
+                {
+                    PDFObjectReference reference = object.getReference();
+                    if (optionalContentGroups.count(reference))
+                    {
+                        const PDFOptionalContentGroup& ocg = optionalContentProperties->getOptionalContentGroup(reference);
+                        return new PDFOptionalContentTreeItem(nullptr, reference, ocg.getName(), lockedOptionalContentGroups.count(reference));
+                    }
+                    else if (!processedReferences.count(reference))
+                    {
+                        processedReferences.insert(reference);
+                        dereferencedObject = m_document->getStorage().getObject(reference);
+                    }
+                    else
+                    {
+                        // Error - we have cyclic references
+                        return nullptr;
+                    }
+                }
+
+                if (dereferencedObject.isArray())
+                {
+                    const PDFArray* array = dereferencedObject.getArray();
+                    const size_t arraySize = array->getCount();
+
+                    // We must have at least one item!
+                    if (arraySize == 0)
+                    {
+                        return nullptr;
+                    }
+
+                    QString text;
+                    size_t i = 0;
+
+                    // Try to retrieve group name
+                    const PDFObject& firstItem = m_document->getObject(array->getItem(0));
+                    if (firstItem.isString())
+                    {
+                        text = loader.readTextString(firstItem, QString());
+                        ++i;
+                    }
+
+                    std::unique_ptr<PDFOptionalContentTreeItem> parentItem(new PDFOptionalContentTreeItem(nullptr, PDFObjectReference(), text, false));
+                    for (; i < arraySize; ++i)
+                    {
+                        if (PDFOptionalContentTreeItem* item = processObject(array->getItem(i)))
+                        {
+                            parentItem->addCreatedChild(item);
+                        }
+                        else
+                        {
+                            // Item cannot be parsed properly
+                            return nullptr;
+                        }
+                    }
+
+                    return parentItem.release();
+                }
+
+                return nullptr;
+            };
+
+            m_rootItem.reset(processObject(orderObject));
+        }
+    }
+
+    endResetModel();
+}
+
+Qt::ItemFlags PDFOptionalContentTreeItemModel::flags(const QModelIndex& index) const
+{
+    Qt::ItemFlags flags = PDFTreeItemModel::flags(index);
+
+    if (!index.isValid())
+    {
+        return flags;
+    }
+
+    const PDFOptionalContentTreeItem* item = static_cast<const PDFOptionalContentTreeItem*>(index.internalPointer());
+    if (item->getReference() != PDFObjectReference())
+    {
+        flags = flags | Qt::ItemIsUserCheckable | Qt::ItemNeverHasChildren;
+
+        if (item->isLocked())
+        {
+            flags &= ~Qt::ItemIsEnabled;
+        }
+    }
+
+    return flags;
+}
+
+QString PDFOptionalContentTreeItem::getText() const
+{
+    if (!m_text.isEmpty())
+    {
+        return m_text;
+    }
+    else if (getParent())
+    {
+        return static_cast<const PDFOptionalContentTreeItem*>(getParent())->getText();
+    }
+
+    return QString();
+}
+
+}   // namespace pdf
diff --git a/PdfForQtLib/sources/pdfitemmodels.h b/PdfForQtLib/sources/pdfitemmodels.h
new file mode 100644
index 0000000..f4bc239
--- /dev/null
+++ b/PdfForQtLib/sources/pdfitemmodels.h
@@ -0,0 +1,123 @@
+//    Copyright (C) 2019 Jakub Melka
+//
+//    This file is part of PdfForQt.
+//
+//    PdfForQt is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Lesser General Public License as published by
+//    the Free Software Foundation, either version 3 of the License, or
+//    (at your option) any later version.
+//
+//    PdfForQt is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//    GNU Lesser General Public License for more details.
+//
+//    You should have received a copy of the GNU Lesser General Public License
+//    along with PDFForQt.  If not, see <https://www.gnu.org/licenses/>.
+
+#ifndef PDFITEMMODELS_H
+#define PDFITEMMODELS_H
+
+#include "pdfglobal.h"
+#include "pdfobject.h"
+
+#include <QAbstractItemModel>
+
+namespace pdf
+{
+class PDFDocument;
+
+/// Represents tree item in the GUI tree
+class PDFTreeItem
+{
+public:
+    inline explicit PDFTreeItem() = default;
+    inline explicit PDFTreeItem(PDFTreeItem* parent) : m_parent(parent) { }
+    virtual ~PDFTreeItem();
+
+    template<typename T, typename... Arguments>
+    inline T* addChild(Arguments&&... arguments)
+    {
+        T* item = new T(this, std::forward(arguments)...);
+        m_children.push_back(item);
+        return item;
+    }
+
+    void addCreatedChild(PDFTreeItem* item)
+    {
+        item->m_parent = this;
+        m_children.push_back(item);
+    }
+
+    int getRow() const { return m_parent->m_children.indexOf(const_cast<PDFTreeItem*>(this)); }
+    int getChildCount() const { return m_children.size(); }
+    const PDFTreeItem* getChild(int index) const { return m_children.at(index); }
+    const PDFTreeItem* getParent() const { return m_parent; }
+
+private:
+    PDFTreeItem* m_parent = nullptr;
+    QList<PDFTreeItem*> m_children;
+};
+
+/// Root of all tree item models
+class PDFFORQTLIBSHARED_EXPORT PDFTreeItemModel : public QAbstractItemModel
+{
+public:
+    explicit PDFTreeItemModel(QObject* parent);
+
+    void setDocument(const pdf::PDFDocument* document);
+
+    bool isEmpty() const;
+
+    virtual QModelIndex index(int row, int column, const QModelIndex& parent) const override;
+    virtual QModelIndex parent(const QModelIndex& child) const override;
+    virtual int rowCount(const QModelIndex& parent) const override;
+    virtual bool hasChildren(const QModelIndex& parent) const override;
+    virtual Qt::ItemFlags flags(const QModelIndex& index) const override;
+    virtual void update() = 0;
+
+protected:
+    const PDFDocument* m_document;
+    std::unique_ptr<PDFTreeItem> m_rootItem;
+};
+
+class PDFOptionalContentTreeItem : public PDFTreeItem
+{
+public:
+    inline explicit PDFOptionalContentTreeItem(PDFOptionalContentTreeItem* parent, PDFObjectReference reference, QString text, bool locked) :
+        PDFTreeItem(parent),
+        m_reference(reference),
+        m_text(qMove(text)),
+        m_locked(locked)
+    {
+
+    }
+
+    PDFObjectReference getReference() const { return m_reference; }
+    QString getText() const;
+    bool isLocked() const { return m_locked; }
+
+private:
+    PDFObjectReference m_reference; ///< Reference to optional content group
+    QString m_text; ///< Node display name
+    bool m_locked; ///< Node is locked (user can't change it)
+};
+
+class PDFFORQTLIBSHARED_EXPORT PDFOptionalContentTreeItemModel : public PDFTreeItemModel
+{
+public:
+    inline explicit PDFOptionalContentTreeItemModel(QObject* parent) :
+        PDFTreeItemModel(parent)
+    {
+
+    }
+
+    virtual int columnCount(const QModelIndex& parent) const override;
+    virtual QVariant data(const QModelIndex& index, int role) const override;
+    virtual void update() override;
+    virtual Qt::ItemFlags flags(const QModelIndex& index) const override;
+};
+
+}   // namespace pdf
+
+#endif // PDFITEMMODELS_H
diff --git a/PdfForQtLib/sources/pdfoptionalcontent.cpp b/PdfForQtLib/sources/pdfoptionalcontent.cpp
index fa308c0..25d1715 100644
--- a/PdfForQtLib/sources/pdfoptionalcontent.cpp
+++ b/PdfForQtLib/sources/pdfoptionalcontent.cpp
@@ -34,6 +34,15 @@ PDFOptionalContentProperties PDFOptionalContentProperties::create(const PDFDocum
         PDFDocumentDataLoaderDecorator loader(document);
         properties.m_allOptionalContentGroups = loader.readReferenceArrayFromDictionary(dictionary, "OCGs");
 
+        for (const PDFObjectReference& reference : properties.m_allOptionalContentGroups)
+        {
+            const PDFObject& object = document->getStorage().getObject(reference);
+            if (!object.isNull())
+            {
+                properties.m_optionalContentGroups[reference] = PDFOptionalContentGroup::create(document, object);
+            }
+        }
+
         if (dictionary->hasKey("D"))
         {
             properties.m_defaultConfiguration = PDFOptionalContentConfiguration::create(document, dictionary->get("D"));
@@ -178,4 +187,91 @@ PDFOptionalContentConfiguration::UsageApplication PDFOptionalContentConfiguratio
     return result;
 }
 
+PDFOptionalContentGroup::PDFOptionalContentGroup() :
+    m_usageZoomMin(0),
+    m_usageZoomMax(std::numeric_limits<PDFReal>::infinity()),
+    m_usagePrintState(OCState::Unknown),
+    m_usageViewState(OCState::Unknown),
+    m_usageExportState(OCState::Unknown)
+{
+
+}
+
+PDFOptionalContentGroup PDFOptionalContentGroup::create(const PDFDocument* document, const PDFObject& object)
+{
+    PDFOptionalContentGroup result;
+
+    const PDFObject& dereferencedObject = document->getObject(object);
+    if (!dereferencedObject.isDictionary())
+    {
+        throw PDFParserException(PDFTranslationContext::tr("Invalid optional content group."));
+    }
+
+    PDFDocumentDataLoaderDecorator loader(document);
+
+    const PDFDictionary* dictionary = dereferencedObject.getDictionary();
+    result.m_name = loader.readTextStringFromDictionary(dictionary, "Name", QString());
+
+    if (dictionary->hasKey("Intent"))
+    {
+        const PDFObject& nameOrNames = document->getObject(dictionary->get("Intent"));
+
+        if (nameOrNames.isName())
+        {
+            result.m_intents = { loader.readName(nameOrNames) };
+        }
+        else if (nameOrNames.isArray())
+        {
+            result.m_intents = loader.readNameArray(nameOrNames);
+        }
+        else if (!nameOrNames.isNull())
+        {
+            throw PDFParserException(PDFTranslationContext::tr("Invalid optional content group."));
+        }
+    }
+
+    const PDFObject& usageDictionaryObject = dictionary->get("Usage");
+    if (usageDictionaryObject.isDictionary())
+    {
+        const PDFDictionary* usageDictionary = usageDictionaryObject.getDictionary();
+
+        result.m_creatorInfo = document->getObject(usageDictionary->get("CreatorInfo"));
+        result.m_language = document->getObject(usageDictionary->get("Language"));
+
+        const PDFObject& zoomDictionary = document->getObject(usageDictionary->get("Zoom"));
+        if (zoomDictionary.isDictionary())
+        {
+            result.m_usageZoomMin = loader.readNumberFromDictionary(usageDictionary, "min", result.m_usageZoomMin);
+            result.m_usageZoomMax = loader.readNumberFromDictionary(usageDictionary, "max", result.m_usageZoomMax);
+        }
+
+        auto readState = [document, usageDictionary, &loader](const char* dictionaryKey, const char* key) -> OCState
+        {
+            const PDFObject& stateDictionaryObject = document->getObject(usageDictionary->get(dictionaryKey));
+            if (stateDictionaryObject.isDictionary())
+            {
+                const PDFDictionary* stateDictionary = stateDictionaryObject.getDictionary();
+                QByteArray stateName = loader.readNameFromDictionary(stateDictionary, key);
+
+                if (stateName == "ON")
+                {
+                    return OCState::ON;
+                }
+                if (stateName == "OFF")
+                {
+                    return OCState::OFF;
+                }
+            }
+
+            return OCState::Unknown;
+        };
+
+        result.m_usageViewState = readState("View", "ViewState");
+        result.m_usagePrintState = readState("Print", "PrintState");
+        result.m_usageExportState = readState("Export", "ExportState");
+    }
+
+    return result;
+}
+
 }   // namespace pdf
diff --git a/PdfForQtLib/sources/pdfoptionalcontent.h b/PdfForQtLib/sources/pdfoptionalcontent.h
index 8b762e9..dd63598 100644
--- a/PdfForQtLib/sources/pdfoptionalcontent.h
+++ b/PdfForQtLib/sources/pdfoptionalcontent.h
@@ -26,6 +26,42 @@ namespace pdf
 
 class PDFDocument;
 
+/// State of the optional content group, or result of expression
+enum class OCState
+{
+    ON,
+    OFF,
+    Unknown
+};
+
+constexpr OCState operator &(OCState left, OCState right)
+{
+    if (left == OCState::Unknown)
+    {
+        return right;
+    }
+    if (right == OCState::Unknown)
+    {
+        return left;
+    }
+
+    return (left == OCState::ON && right == OCState::ON) ? OCState::ON : OCState::OFF;
+}
+
+constexpr OCState operator |(OCState left, OCState right)
+{
+    if (left == OCState::Unknown)
+    {
+        return right;
+    }
+    if (right == OCState::Unknown)
+    {
+        return left;
+    }
+
+    return (left == OCState::ON || right == OCState::ON) ? OCState::ON : OCState::OFF;
+}
+
 /// Configuration of optional content configuration.
 class PDFOptionalContentConfiguration
 {
@@ -57,6 +93,18 @@ public:
     /// \param object Object containing documents optional content configuration
     static PDFOptionalContentConfiguration create(const PDFDocument* document, const PDFObject& object);
 
+    const QString& getName() const { return m_name; }
+    const QString& getCreator() const { return m_creator; }
+    BaseState getBaseState() const { return m_baseState; }
+    const std::vector<PDFObjectReference>& getOnArray() const { return m_OnArray; }
+    const std::vector<PDFObjectReference>& getOffArray() const { return m_OffArray; }
+    const std::vector<QByteArray>& getIntents() const { return m_intents; }
+    const std::vector<UsageApplication>& getUsageApplications() const { return m_usageApplications; }
+    const PDFObject& getOrder() const { return m_order; }
+    ListMode getListMode() const { return m_listMode; }
+    const std::vector<std::vector<PDFObjectReference>>& getRadioButtonGroups() const { return m_radioButtonGroups; }
+    const std::vector<PDFObjectReference>& getLocked() const { return m_locked; }
+
 private:
     /// Creates usage application
     /// \param document Document
@@ -76,6 +124,43 @@ private:
     std::vector<PDFObjectReference> m_locked;
 };
 
+/// Class reprezenting optional content group - it contains properties of the group,
+/// such as name, usage etc.
+class PDFOptionalContentGroup
+{
+public:
+    explicit PDFOptionalContentGroup();
+
+    /// Creates optional content group from the object. Object must be valid optional
+    /// content group, if it is invalid, then exception is thrown.
+    /// \param document Document
+    /// \param object Object containing optional content group
+    static PDFOptionalContentGroup create(const PDFDocument* document, const PDFObject& object);
+
+    PDFObjectReference getReference() const { return m_reference; }
+    const QString& getName() const { return m_name; }
+    const std::vector<QByteArray>& getIntents() const { return m_intents; }
+    PDFObject getCreatorInfo() const { return m_creatorInfo; }
+    PDFObject getLanguage() const { return m_language; }
+    PDFReal getUsageZoomMin() const { return m_usageZoomMin; }
+    PDFReal getUsageZoomMax() const { return m_usageZoomMax; }
+    OCState getUsagePrintState() const { return m_usagePrintState; }
+    OCState getUsageViewState() const { return m_usageViewState; }
+    OCState getUsageExportState() const { return m_usageExportState; }
+
+private:
+    PDFObjectReference m_reference;
+    QString m_name;
+    std::vector<QByteArray> m_intents;
+    PDFObject m_creatorInfo;
+    PDFObject m_language;
+    PDFReal m_usageZoomMin;
+    PDFReal m_usageZoomMax;
+    OCState m_usagePrintState;
+    OCState m_usageViewState;
+    OCState m_usageExportState;
+};
+
 /// Object containing properties of the optional content of the PDF document. It contains
 /// for example all documents optional content groups.
 class PDFOptionalContentProperties
@@ -84,7 +169,7 @@ public:
     explicit PDFOptionalContentProperties() = default;
 
     /// Returns, if object is valid - at least one optional content group exists
-    bool isValid() const { return !m_allOptionalContentGroups.empty(); }
+    bool isValid() const { return !m_allOptionalContentGroups.empty() && m_allOptionalContentGroups.size() == m_optionalContentGroups.size(); }
 
     /// Creates new optional content properties from the object. If object is not valid,
     /// then exception is thrown.
@@ -92,10 +177,15 @@ public:
     /// \param object Object containing documents optional content properties
     static PDFOptionalContentProperties create(const PDFDocument* document, const PDFObject& object);
 
+    const std::vector<PDFObjectReference>& getAllOptionalContentGroups() const { return m_allOptionalContentGroups; }
+    const PDFOptionalContentConfiguration& getDefaultConfiguration() const { return m_defaultConfiguration; }
+    const PDFOptionalContentGroup& getOptionalContentGroup(PDFObjectReference reference) const { return m_optionalContentGroups.at(reference); }
+
 private:
     std::vector<PDFObjectReference> m_allOptionalContentGroups;
     PDFOptionalContentConfiguration m_defaultConfiguration;
     std::vector<PDFOptionalContentConfiguration> m_configurations;
+    std::map<PDFObjectReference, PDFOptionalContentGroup> m_optionalContentGroups;
 };
 
 }   // namespace pdf
diff --git a/PdfForQtViewer/pdfviewermainwindow.cpp b/PdfForQtViewer/pdfviewermainwindow.cpp
index c8b1c46..8cd6a55 100644
--- a/PdfForQtViewer/pdfviewermainwindow.cpp
+++ b/PdfForQtViewer/pdfviewermainwindow.cpp
@@ -25,6 +25,7 @@
 #include "pdfdrawspacecontroller.h"
 #include "pdfrenderingerrorswidget.h"
 #include "pdffont.h"
+#include "pdfitemmodels.h"
 
 #include <QSettings>
 #include <QFileDialog>
@@ -33,6 +34,10 @@
 #include <QApplication>
 #include <QDesktopWidget>
 #include <QStandardPaths>
+#include <QDockWidget>
+#include <QTreeView>
+#include <QLayout>
+#include <QHeaderView>
 
 namespace pdfviewer
 {
@@ -40,7 +45,10 @@ namespace pdfviewer
 PDFViewerMainWindow::PDFViewerMainWindow(QWidget *parent) :
     QMainWindow(parent),
     ui(new Ui::PDFViewerMainWindow),
-    m_pdfWidget(nullptr)
+    m_pdfWidget(nullptr),
+    m_optionalContentDockWidget(nullptr),
+    m_optionalContentTreeView(nullptr),
+    m_optionalContentTreeModel(nullptr)
 {
     ui->setupUi(this);
 
@@ -77,6 +85,19 @@ PDFViewerMainWindow::PDFViewerMainWindow(QWidget *parent) :
     setCentralWidget(m_pdfWidget);
     setFocusProxy(m_pdfWidget);
 
+    m_optionalContentDockWidget = new QDockWidget(tr("Optional Content"), this);
+    m_optionalContentDockWidget->setObjectName("OptionalContentDockWidget");
+    m_optionalContentDockWidget->setAllowedAreas(Qt::LeftDockWidgetArea | Qt::RightDockWidgetArea);
+    m_optionalContentTreeView = new QTreeView(m_optionalContentDockWidget);
+    m_optionalContentTreeView->header()->hide();
+    m_optionalContentTreeModel = new pdf::PDFOptionalContentTreeItemModel(m_optionalContentTreeView);
+    m_optionalContentTreeView->setModel(m_optionalContentTreeModel);
+    m_optionalContentDockWidget->setWidget(m_optionalContentTreeView);
+    addDockWidget(Qt::LeftDockWidgetArea, m_optionalContentDockWidget);
+
+    ui->menuView->addSeparator();
+    ui->menuView->addAction(m_optionalContentDockWidget->toggleViewAction());
+
     connect(m_pdfWidget->getDrawWidgetProxy(), &pdf::PDFDrawWidgetProxy::pageLayoutChanged, this, &PDFViewerMainWindow::updatePageLayoutActions);
     connect(m_pdfWidget, &pdf::PDFWidget::pageRenderingErrorsChanged, this, &PDFViewerMainWindow::onPageRenderingErrorsChanged, Qt::QueuedConnection);
 
@@ -234,6 +255,18 @@ void PDFViewerMainWindow::openDocument(const QString& fileName)
 void PDFViewerMainWindow::setDocument(const pdf::PDFDocument* document)
 {
     m_pdfWidget->setDocument(document);
+    m_optionalContentTreeModel->setDocument(document);
+    m_optionalContentTreeView->expandAll();
+
+    if (m_optionalContentTreeModel->isEmpty())
+    {
+        m_optionalContentDockWidget->hide();
+    }
+    else
+    {
+        m_optionalContentDockWidget->show();
+    }
+
     updateTitle();
 }
 
diff --git a/PdfForQtViewer/pdfviewermainwindow.h b/PdfForQtViewer/pdfviewermainwindow.h
index 1dc3810..2f0baf3 100644
--- a/PdfForQtViewer/pdfviewermainwindow.h
+++ b/PdfForQtViewer/pdfviewermainwindow.h
@@ -21,6 +21,7 @@
 #include "pdfcatalog.h"
 #include "pdfrenderer.h"
 
+#include <QTreeView>
 #include <QMainWindow>
 #include <QSharedPointer>
 
@@ -33,6 +34,7 @@ namespace pdf
 {
 class PDFWidget;
 class PDFDocument;
+class PDFOptionalContentTreeItemModel;
 }
 
 namespace pdfviewer
@@ -82,6 +84,9 @@ private:
     QSharedPointer<pdf::PDFDocument> m_pdfDocument;
     QString m_directory;
     QString m_currentFile;
+    QDockWidget* m_optionalContentDockWidget;
+    QTreeView* m_optionalContentTreeView;
+    pdf::PDFOptionalContentTreeItemModel* m_optionalContentTreeModel;
 };
 
 }   // namespace pdfviewer