diff --git a/gui/designwidget.cc b/gui/designwidget.cc
new file mode 100644
index 00000000..4d8cee50
--- /dev/null
+++ b/gui/designwidget.cc
@@ -0,0 +1,233 @@
+#include "designwidget.h"
+#include <QAction>
+#include <QGridLayout>
+#include <QMenu>
+#include <QSplitter>
+#include <QTreeWidgetItem>
+#include "fpgaviewwidget.h"
+#include "pybindings.h"
+
+enum class ElementType
+{
+    BEL,
+    WIRE,
+    PIP
+};
+
+class ElementTreeItem : public QTreeWidgetItem
+{
+  public:
+    ElementTreeItem(ElementType t, QString str)
+            : QTreeWidgetItem((QTreeWidget *)nullptr, QStringList(str)), type(t)
+    {
+    }
+    virtual ~ElementTreeItem(){};
+
+    ElementType getType() { return type; };
+
+  private:
+    ElementType type;
+};
+
+class BelTreeItem : public ElementTreeItem
+{
+  public:
+    BelTreeItem(IdString d, ElementType type, QString str)
+            : ElementTreeItem(type, str)
+    {
+        this->data = d;
+    }
+    virtual ~BelTreeItem(){};
+
+    IdString getData() { return this->data; };
+
+  private:
+    IdString data;
+};
+
+class WireTreeItem : public ElementTreeItem
+{
+  public:
+    WireTreeItem(IdString d, ElementType type, QString str)
+            : ElementTreeItem(type, str)
+    {
+        this->data = d;
+    }
+    virtual ~WireTreeItem(){};
+
+    IdString getData() { return this->data; };
+
+  private:
+    IdString data;
+};
+
+class PipTreeItem : public ElementTreeItem
+{
+  public:
+    PipTreeItem(IdString d, ElementType type, QString str)
+            : ElementTreeItem(type, str)
+    {
+        this->data = d;
+    }
+    virtual ~PipTreeItem(){};
+
+    IdString getData() { return this->data; };
+
+  private:
+    IdString data;
+};
+
+DesignWidget::DesignWidget(Design *_design, QWidget *parent)
+        : QWidget(parent), design(_design)
+{
+
+    treeWidget = new QTreeWidget();
+
+    // Add tree view
+    treeWidget->setColumnCount(1);
+    treeWidget->setHeaderLabel(QString("Items"));
+    treeWidget->setContextMenuPolicy(Qt::CustomContextMenu);
+
+    // Add bels to tree
+    QTreeWidgetItem *bel_root = new QTreeWidgetItem(treeWidget);
+    bel_root->setText(0, QString("Bels"));
+    treeWidget->insertTopLevelItem(0, bel_root);
+    QList<QTreeWidgetItem *> bel_items;
+    for (auto bel : design->chip.getBels()) {
+        auto name = design->chip.getBelName(bel);
+        bel_items.append(
+                new BelTreeItem(name, ElementType::BEL, QString(name.c_str())));
+    }
+    bel_root->addChildren(bel_items);
+
+    // Add wires to tree
+    QTreeWidgetItem *wire_root = new QTreeWidgetItem(treeWidget);
+    QList<QTreeWidgetItem *> wire_items;
+    wire_root->setText(0, QString("Wires"));
+    treeWidget->insertTopLevelItem(0, wire_root);
+    for (auto wire : design->chip.getWires()) {
+        auto name = design->chip.getWireName(wire);
+        wire_items.append(new WireTreeItem(name, ElementType::WIRE,
+                                           QString(name.c_str())));
+    }
+    wire_root->addChildren(wire_items);
+
+    // Add pips to tree
+    QTreeWidgetItem *pip_root = new QTreeWidgetItem(treeWidget);
+    QList<QTreeWidgetItem *> pip_items;
+    pip_root->setText(0, QString("Pips"));
+    treeWidget->insertTopLevelItem(0, pip_root);
+    for (auto pip : design->chip.getPips()) {
+        auto name = design->chip.getPipName(pip);
+        pip_items.append(
+                new PipTreeItem(name, ElementType::PIP, QString(name.c_str())));
+    }
+    pip_root->addChildren(pip_items);
+
+    // Add property view
+    variantManager = new QtVariantPropertyManager();
+    variantFactory = new QtVariantEditorFactory();
+    propertyEditor = new QtTreePropertyBrowser();
+    propertyEditor->setFactoryForManager(variantManager, variantFactory);
+    propertyEditor->setPropertiesWithoutValueMarked(true);
+    propertyEditor->setRootIsDecorated(false);
+
+    propertyEditor->show();
+
+    QSplitter *splitter = new QSplitter(Qt::Vertical);
+    splitter->addWidget(treeWidget);
+    splitter->addWidget(propertyEditor);
+
+    QGridLayout *mainLayout = new QGridLayout();
+    mainLayout->addWidget(splitter);
+    setLayout(mainLayout);
+
+    // Connection
+    connect(treeWidget, &QTreeWidget::customContextMenuRequested, this,
+            &DesignWidget::prepareMenu);
+
+    connect(treeWidget, SIGNAL(itemClicked(QTreeWidgetItem *, int)),
+            SLOT(onItemClicked(QTreeWidgetItem *, int)));
+}
+
+DesignWidget::~DesignWidget()
+{
+    delete variantManager;
+    delete variantFactory;
+    delete propertyEditor;
+}
+
+void DesignWidget::addProperty(QtVariantProperty *property, const QString &id)
+{
+    propertyToId[property] = id;
+    idToProperty[id] = property;
+    QtBrowserItem *item = propertyEditor->addProperty(property);
+}
+
+void DesignWidget::clearProperties()
+{
+    QMap<QtProperty *, QString>::ConstIterator itProp =
+            propertyToId.constBegin();
+    while (itProp != propertyToId.constEnd()) {
+        delete itProp.key();
+        itProp++;
+    }
+    propertyToId.clear();
+    idToProperty.clear();
+}
+
+void DesignWidget::onItemClicked(QTreeWidgetItem *item, int pos)
+{
+    if (!item->parent())
+        return;
+
+    clearProperties();
+
+    ElementType type = static_cast<ElementTreeItem *>(item)->getType();
+
+    if (type == ElementType::BEL) {
+        IdString c = static_cast<BelTreeItem *>(item)->getData();
+
+        QtVariantProperty *topItem =
+                variantManager->addProperty(QVariant::String, QString("Name"));
+        topItem->setValue(QString(c.c_str()));
+        addProperty(topItem, QString("Name"));
+    } else if (type == ElementType::WIRE) {
+        IdString c = static_cast<WireTreeItem *>(item)->getData();
+
+        QtVariantProperty *topItem =
+                variantManager->addProperty(QVariant::String, QString("Name"));
+        topItem->setValue(QString(c.c_str()));
+        addProperty(topItem, QString("Name"));
+
+    } else if (type == ElementType::PIP) {
+        IdString c = static_cast<PipTreeItem *>(item)->getData();
+
+        QtVariantProperty *topItem =
+                variantManager->addProperty(QVariant::String, QString("Name"));
+        topItem->setValue(QString(c.c_str()));
+        addProperty(topItem, QString("Name"));
+    }
+}
+
+void DesignWidget::prepareMenu(const QPoint &pos)
+{
+    QTreeWidget *tree = treeWidget;
+
+    itemContextMenu = tree->itemAt(pos);
+
+    QAction *selectAction = new QAction("&Select", this);
+    selectAction->setStatusTip("Select item on view");
+    connect(selectAction, SIGNAL(triggered()), this, SLOT(selectObject()));
+
+    QMenu menu(this);
+    menu.addAction(selectAction);
+
+    QPoint pt(pos);
+    menu.exec(tree->mapToGlobal(pos));
+}
+
+void DesignWidget::selectObject()
+{
+    // info->info("selected " + itemContextMenu->text(0).toStdString() + "\n");
+}
diff --git a/gui/designwidget.h b/gui/designwidget.h
new file mode 100644
index 00000000..e237ec6d
--- /dev/null
+++ b/gui/designwidget.h
@@ -0,0 +1,45 @@
+#ifndef DESIGNWIDGET_H
+#define DESIGNWIDGET_H
+
+#include <QTreeWidget>
+#include "nextpnr.h"
+#include "qtpropertymanager.h"
+#include "qttreepropertybrowser.h"
+#include "qtvariantproperty.h"
+
+// FIXME
+USING_NEXTPNR_NAMESPACE
+
+class DesignWidget : public QWidget
+{
+    Q_OBJECT
+
+  public:
+    explicit DesignWidget(Design *design, QWidget *parent = 0);
+    ~DesignWidget();
+    Design *getDesign() { return design; }
+
+  private:
+    void addProperty(QtVariantProperty *property, const QString &id);
+    void clearProperties();
+
+  private Q_SLOTS:
+    void prepareMenu(const QPoint &pos);
+    void selectObject();
+    void onItemClicked(QTreeWidgetItem *item, int);
+
+  private:
+    Design *design;
+
+    QTreeWidget *treeWidget;
+
+    QtVariantPropertyManager *variantManager;
+    QtVariantEditorFactory *variantFactory;
+    QtTreePropertyBrowser *propertyEditor;
+    QTreeWidgetItem *itemContextMenu;
+
+    QMap<QtProperty *, QString> propertyToId;
+    QMap<QString, QtVariantProperty *> idToProperty;
+};
+
+#endif // DESIGNWIDGET_H
diff --git a/gui/gui.cmake b/gui/gui.cmake
index 5b9b1833..45402c1c 100644
--- a/gui/gui.cmake
+++ b/gui/gui.cmake
@@ -11,12 +11,14 @@ qt5_generate_moc(gui/mainwindow.h ${CMAKE_CURRENT_BINARY_DIR}/generated/moc_main
 qt5_generate_moc(gui/fpgaviewwidget.h ${CMAKE_CURRENT_BINARY_DIR}/generated/moc_fpgaviewwidget.cc)
 qt5_generate_moc(gui/pythontab.h ${CMAKE_CURRENT_BINARY_DIR}/generated/moc_pythontab.cc)
 qt5_generate_moc(gui/infotab.h ${CMAKE_CURRENT_BINARY_DIR}/generated/moc_infotab.cc)
+qt5_generate_moc(gui/designwidget.h ${CMAKE_CURRENT_BINARY_DIR}/generated/moc_designwidget.cc)
 
 set(GENERATED_MOC_FILES
     ${CMAKE_CURRENT_BINARY_DIR}/generated/moc_mainwindow.cc
     ${CMAKE_CURRENT_BINARY_DIR}/generated/moc_fpgaviewwidget.cc
     ${CMAKE_CURRENT_BINARY_DIR}/generated/moc_pythontab.cc
     ${CMAKE_CURRENT_BINARY_DIR}/generated/moc_infotab.cc
+    ${CMAKE_CURRENT_BINARY_DIR}/generated/moc_designwidget.cc
 )
 
 set(UI_SOURCES
@@ -25,7 +27,7 @@ set(UI_SOURCES
 qt5_wrap_ui_custom(GENERATED_UI_HEADERS ${UI_SOURCES})
 qt5_add_resources_custom(GUI_RESOURCE_FILES gui/nextpnr.qrc)
 
-set(GUI_SOURCE_FILES gui/mainwindow.cc gui/fpgaviewwidget.cc gui/pythontab.cc gui/infotab.cc gui/emb.cc ${GENERATED_MOC_FILES} ${GENERATED_UI_HEADERS} ${GUI_RESOURCE_FILES})
+set(GUI_SOURCE_FILES gui/mainwindow.cc gui/fpgaviewwidget.cc gui/pythontab.cc gui/infotab.cc gui/designwidget.cc gui/emb.cc ${GENERATED_MOC_FILES} ${GENERATED_UI_HEADERS} ${GUI_RESOURCE_FILES})
 set(GUI_LIBRARY_FILES Qt5::Widgets Qt5::OpenGL ${OPENGL_LIBRARIES} QtPropertyBrowser)
 
 
diff --git a/gui/mainwindow.cc b/gui/mainwindow.cc
index c8d072bb..e41da79a 100644
--- a/gui/mainwindow.cc
+++ b/gui/mainwindow.cc
@@ -1,84 +1,9 @@
 #include "mainwindow.h"
-#include <functional>
-#include <iostream>
-#include <string>
-#include "emb.h"
-#include "pybindings.h"
+#include "designwidget.h"
+#include "fpgaviewwidget.h"
+#include "pythontab.h"
 #include "ui_mainwindow.h"
 
-#include <QDate>
-#include <QLocale>
-
-enum class ElementType
-{
-    BEL,
-    WIRE,
-    PIP
-};
-
-class ElementTreeItem : public QTreeWidgetItem
-{
-  public:
-    ElementTreeItem(ElementType t, QString str)
-            : QTreeWidgetItem((QTreeWidget *)nullptr, QStringList(str)), type(t)
-    {
-    }
-    virtual ~ElementTreeItem(){};
-
-    ElementType getType() { return type; };
-
-  private:
-    ElementType type;
-};
-
-class BelTreeItem : public ElementTreeItem
-{
-  public:
-    BelTreeItem(IdString d, ElementType type, QString str)
-            : ElementTreeItem(type, str)
-    {
-        this->data = d;
-    }
-    virtual ~BelTreeItem(){};
-
-    IdString getData() { return this->data; };
-
-  private:
-    IdString data;
-};
-
-class WireTreeItem : public ElementTreeItem
-{
-  public:
-    WireTreeItem(IdString d, ElementType type, QString str)
-            : ElementTreeItem(type, str)
-    {
-        this->data = d;
-    }
-    virtual ~WireTreeItem(){};
-
-    IdString getData() { return this->data; };
-
-  private:
-    IdString data;
-};
-
-class PipTreeItem : public ElementTreeItem
-{
-  public:
-    PipTreeItem(IdString d, ElementType type, QString str)
-            : ElementTreeItem(type, str)
-    {
-        this->data = d;
-    }
-    virtual ~PipTreeItem(){};
-
-    IdString getData() { return this->data; };
-
-  private:
-    IdString data;
-};
-
 MainWindow::MainWindow(Design *_design, QWidget *parent)
         : QMainWindow(parent), ui(new Ui::MainWindow), design(_design)
 {
@@ -86,61 +11,11 @@ MainWindow::MainWindow(Design *_design, QWidget *parent)
     std::string title = "nextpnr-ice40 - " + design->chip.getChipName();
     setWindowTitle(title.c_str());
 
-    // Add tree view
-    ui->treeWidget->setColumnCount(1);
-    ui->treeWidget->setHeaderLabel(QString("Items"));
-    ui->treeWidget->setContextMenuPolicy(Qt::CustomContextMenu);
-    connect(ui->treeWidget, &QTreeWidget::customContextMenuRequested, this,
-            &MainWindow::prepareMenu);
+    ui->splitter->addWidget(new FPGAViewWidget());
 
-    // Add bels to tree
-    QTreeWidgetItem *bel_root = new QTreeWidgetItem(ui->treeWidget);
-    bel_root->setText(0, QString("Bels"));
-    ui->treeWidget->insertTopLevelItem(0, bel_root);
-    QList<QTreeWidgetItem *> bel_items;
-    for (auto bel : design->chip.getBels()) {
-        auto name = design->chip.getBelName(bel);
-        bel_items.append(
-                new BelTreeItem(name, ElementType::BEL, QString(name.c_str())));
-    }
-    bel_root->addChildren(bel_items);
-
-    // Add wires to tree
-    QTreeWidgetItem *wire_root = new QTreeWidgetItem(ui->treeWidget);
-    QList<QTreeWidgetItem *> wire_items;
-    wire_root->setText(0, QString("Wires"));
-    ui->treeWidget->insertTopLevelItem(0, wire_root);
-    for (auto wire : design->chip.getWires()) {
-        auto name = design->chip.getWireName(wire);
-        wire_items.append(new WireTreeItem(name, ElementType::WIRE,
-                                           QString(name.c_str())));
-    }
-    wire_root->addChildren(wire_items);
-
-    // Add pips to tree
-    QTreeWidgetItem *pip_root = new QTreeWidgetItem(ui->treeWidget);
-    QList<QTreeWidgetItem *> pip_items;
-    pip_root->setText(0, QString("Pips"));
-    ui->treeWidget->insertTopLevelItem(0, pip_root);
-    for (auto pip : design->chip.getPips()) {
-        auto name = design->chip.getPipName(pip);
-        pip_items.append(
-                new PipTreeItem(name, ElementType::PIP, QString(name.c_str())));
-    }
-    pip_root->addChildren(pip_items);
-
-    // Add property view
-    variantManager = new QtVariantPropertyManager();
-    variantFactory = new QtVariantEditorFactory();
-    propertyEditor = new QtTreePropertyBrowser();
-    propertyEditor->setFactoryForManager(variantManager, variantFactory);
-    propertyEditor->setPropertiesWithoutValueMarked(true);
-    propertyEditor->setRootIsDecorated(false);
-    propertyEditor->show();
-    ui->splitter_2->addWidget(propertyEditor);
-
-    connect(ui->treeWidget, SIGNAL(itemClicked(QTreeWidgetItem *, int)),
-            SLOT(onItemClicked(QTreeWidgetItem *, int)));
+    ui->splitter_2->addWidget(new DesignWidget(design));
+    ui->splitter_2->setMinimumWidth(300);
+    ui->splitter_2->setMaximumWidth(300);
 
     tabWidget = new QTabWidget();
     tabWidget->addTab(new PythonTab(), "Python");
@@ -149,85 +24,4 @@ MainWindow::MainWindow(Design *_design, QWidget *parent)
     ui->splitter->addWidget(tabWidget);
 }
 
-MainWindow::~MainWindow()
-{
-    delete variantManager;
-    delete variantFactory;
-    delete propertyEditor;
-    delete ui;
-}
-
-void MainWindow::addProperty(QtVariantProperty *property, const QString &id)
-{
-    propertyToId[property] = id;
-    idToProperty[id] = property;
-    QtBrowserItem *item = propertyEditor->addProperty(property);
-}
-
-void MainWindow::clearProperties()
-{
-    QMap<QtProperty *, QString>::ConstIterator itProp =
-            propertyToId.constBegin();
-    while (itProp != propertyToId.constEnd()) {
-        delete itProp.key();
-        itProp++;
-    }
-    propertyToId.clear();
-    idToProperty.clear();
-}
-
-void MainWindow::onItemClicked(QTreeWidgetItem *item, int pos)
-{
-    if (!item->parent())
-        return;
-
-    clearProperties();
-
-    ElementType type = static_cast<ElementTreeItem *>(item)->getType();
-
-    if (type == ElementType::BEL) {
-        IdString c = static_cast<BelTreeItem *>(item)->getData();
-
-        QtVariantProperty *topItem =
-                variantManager->addProperty(QVariant::String, QString("Name"));
-        topItem->setValue(QString(c.c_str()));
-        addProperty(topItem, QString("Name"));
-    } else if (type == ElementType::WIRE) {
-        IdString c = static_cast<WireTreeItem *>(item)->getData();
-
-        QtVariantProperty *topItem =
-                variantManager->addProperty(QVariant::String, QString("Name"));
-        topItem->setValue(QString(c.c_str()));
-        addProperty(topItem, QString("Name"));
-
-    } else if (type == ElementType::PIP) {
-        IdString c = static_cast<PipTreeItem *>(item)->getData();
-
-        QtVariantProperty *topItem =
-                variantManager->addProperty(QVariant::String, QString("Name"));
-        topItem->setValue(QString(c.c_str()));
-        addProperty(topItem, QString("Name"));
-    }
-}
-
-void MainWindow::prepareMenu(const QPoint &pos)
-{
-    QTreeWidget *tree = ui->treeWidget;
-
-    itemContextMenu = tree->itemAt(pos);
-
-    QAction *selectAction = new QAction("&Select", this);
-    selectAction->setStatusTip("Select item on view");
-    connect(selectAction, SIGNAL(triggered()), this, SLOT(selectObject()));
-
-    QMenu menu(this);
-    menu.addAction(selectAction);
-
-    QPoint pt(pos);
-    menu.exec(tree->mapToGlobal(pos));
-}
-
-void MainWindow::selectObject()
-{
-    info->info("selected " + itemContextMenu->text(0).toStdString() + "\n");
-}
+MainWindow::~MainWindow() { delete ui; }
diff --git a/gui/mainwindow.h b/gui/mainwindow.h
index d9397b5c..37d8b566 100644
--- a/gui/mainwindow.h
+++ b/gui/mainwindow.h
@@ -1,16 +1,10 @@
 #ifndef MAINWINDOW_H
 #define MAINWINDOW_H
 
-#include "emb.h"
 #include "infotab.h"
 #include "nextpnr.h"
-#include "pythontab.h"
-#include "qtpropertymanager.h"
-#include "qttreepropertybrowser.h"
-#include "qtvariantproperty.h"
 
 #include <QMainWindow>
-#include <QPlainTextEdit>
 #include <QTabWidget>
 
 // FIXME
@@ -29,25 +23,10 @@ class MainWindow : public QMainWindow
     ~MainWindow();
     Design *getDesign() { return design; }
 
-  private:
-    void addProperty(QtVariantProperty *property, const QString &id);
-    void clearProperties();
-
   private Q_SLOTS:
-    void prepareMenu(const QPoint &pos);
-    void selectObject();
-    void onItemClicked(QTreeWidgetItem *item, int);
-
   private:
     Ui::MainWindow *ui;
     Design *design;
-    QtVariantPropertyManager *variantManager;
-    QtVariantEditorFactory *variantFactory;
-    QtTreePropertyBrowser *propertyEditor;
-    QTreeWidgetItem *itemContextMenu;
-
-    QMap<QtProperty *, QString> propertyToId;
-    QMap<QString, QtVariantProperty *> idToProperty;
 
     QTabWidget *tabWidget;
     InfoTab *info;
diff --git a/gui/mainwindow.ui b/gui/mainwindow.ui
index aed4b47f..7260c7ea 100644
--- a/gui/mainwindow.ui
+++ b/gui/mainwindow.ui
@@ -24,26 +24,11 @@
        <property name="orientation">
         <enum>Qt::Vertical</enum>
        </property>
-       <widget class="FPGAViewWidget" name="openGLWidget" native="true"/>
       </widget>
       <widget class="QSplitter" name="splitter_2">
        <property name="orientation">
         <enum>Qt::Vertical</enum>
        </property>       
-       <widget class="QTreeWidget" name="treeWidget">
-        <property name="minimumSize">
-         <size>
-          <width>300</width>
-          <height>0</height>
-         </size>
-        </property>
-        <property name="maximumSize">
-         <size>
-          <width>300</width>
-          <height>16777215</height>
-         </size>
-        </property>
-       </widget>
       </widget>
      </widget>
     </item>
@@ -144,13 +129,6 @@
   </action>
  </widget>
  <layoutdefault spacing="6" margin="11"/>
- <customwidgets>
-  <customwidget>
-   <class>FPGAViewWidget</class>
-   <extends>QWidget</extends>
-   <header>fpgaviewwidget.h</header>
-  </customwidget>
- </customwidgets>
  <resources>
   <include location="nextpnr.qrc"/>
  </resources>