diff --git a/src/gui2/drivecomponent.cc b/src/gui2/drivecomponent.cc
index b17f054b..0ad7315b 100644
--- a/src/gui2/drivecomponent.cc
+++ b/src/gui2/drivecomponent.cc
@@ -6,6 +6,7 @@
 #include "driveConfigurationForm.h"
 #include "fluxConfigurationForm.h"
 #include <QStandardItemModel>
+#include <range/v3/all.hpp>
 
 static const char* DRIVE = "drive/";
 static const char* SELECTED_DRIVE = "drive/drive";
@@ -96,6 +97,33 @@ public:
                 &QLineEdit::editingFinished,
                 this,
                 &ConfigurationForm::updateSavedState);
+
+            connect(openButton,
+                &QPushButton::clicked,
+                [this]()
+                {
+                    std::string formats = Config::getFluxFormats() |
+                                          ranges::views::transform(
+                                              [](const FluxConstructor& f)
+                                              {
+                                                  return f.glob;
+                                              }) |
+                                          ranges::views::filter(
+                                              [](const std::string& s)
+                                              {
+                                                  return !s.empty();
+                                              }) |
+                                          ranges::views::intersperse(" ") |
+                                          ranges::views::join |
+                                          ranges::to<std::string>();
+                    QFileDialog dialogue(_dci->container());
+                    dialogue.setFileMode(QFileDialog::ExistingFile);
+                    dialogue.setNameFilter(QString::fromStdString("Flux files (" + formats + ")"));
+
+                    QStringList fileNames;
+                    if (dialogue.exec())
+                        filenameEdit->setText(dialogue.selectedFiles().first());
+                });
         }
 
         void updateSavedState() const override
diff --git a/src/gui2/fluxConfigurationForm.ui b/src/gui2/fluxConfigurationForm.ui
index 63fdf942..67df7047 100644
--- a/src/gui2/fluxConfigurationForm.ui
+++ b/src/gui2/fluxConfigurationForm.ui
@@ -33,7 +33,7 @@
       <widget class="QLineEdit" name="filenameEdit"/>
      </item>
      <item>
-      <widget class="QToolButton" name="toolButton_7">
+      <widget class="QToolButton" name="openButton">
        <property name="text">
         <string>Open</string>
        </property>
@@ -111,6 +111,9 @@
      </item>
      <item>
       <widget class="QSpinBox" name="spinBox">
+       <property name="enabled">
+        <bool>false</bool>
+       </property>
        <property name="sizePolicy">
         <sizepolicy hsizetype="Expanding" vsizetype="Fixed">
          <horstretch>0</horstretch>
diff --git a/src/gui2/mainwindow.cc b/src/gui2/mainwindow.cc
index 68eea24e..0657fe86 100644
--- a/src/gui2/mainwindow.cc
+++ b/src/gui2/mainwindow.cc
@@ -1,6 +1,7 @@
 #include "lib/globals.h"
 #include "lib/config.h"
 #include "lib/readerwriter.h"
+#include "lib/utils.h"
 #include "globals.h"
 #include "mainwindow.h"
 #include "drivecomponent.h"
@@ -12,6 +13,14 @@ class MainWindowImpl : public MainWindow
 {
     W_OBJECT(MainWindowImpl)
 
+private:
+    enum State
+    {
+        STATE_IDLE,
+        STATE_READING,
+        STATE_WRITING
+    };
+
 public:
     MainWindowImpl()
     {
@@ -31,14 +40,20 @@ public:
         _progressWidget->setAlignment(Qt::AlignRight);
         statusbar->addPermanentWidget(_progressWidget);
 
-        auto* stopWidget = new QToolButton();
-        stopWidget->setText("Stop");
-        statusbar->addPermanentWidget(stopWidget);
+        _stopWidget = new QToolButton();
+        _stopWidget->setText("Stop");
+        statusbar->addPermanentWidget(_stopWidget);
 
         connect(readDiskButton,
             &QAbstractButton::clicked,
             this,
             &MainWindowImpl::readDisk);
+        connect(_stopWidget,
+            &QPushButton::clicked,
+            this,
+            &MainWindowImpl::emergencyStop);
+
+        setState(STATE_IDLE);
     }
 
 public:
@@ -61,24 +76,24 @@ public:
                        {
                            _fluxComponent->setDiskData(m.disk);
                            _imageComponent->setDiskData(m.disk);
+                           _currentDisk = m.disk;
                        },
 
                        /* Large-scale operation start. */
                        [this](const BeginOperationLogMessage& m)
                        {
-                           setProgressBar(0);
+                           _progressWidget->setValue(0);
                        },
 
                        /* Large-scale operation end. */
                        [this](const EndOperationLogMessage& m)
                        {
-                           finishedWithProgressBar();
                        },
 
                        /* Large-scale operation progress. */
                        [this](const OperationProgressLogMessage& m)
                        {
-                           setProgressBar(m.progress);
+                           _progressWidget->setValue(m.progress);
                        }},
             *message);
 
@@ -87,18 +102,6 @@ public:
         logViewerEdit->ensureCursorVisible();
     }
 
-    void setProgressBar(int progress) override
-    {
-        _progressWidget->setEnabled(true);
-        _progressWidget->setValue(progress);
-    }
-
-    void finishedWithProgressBar() override
-    {
-        _progressWidget->setEnabled(false);
-        _progressWidget->setValue(0);
-    }
-
     void collectConfig() override
     {
         try
@@ -113,9 +116,7 @@ public:
         }
         catch (...)
         {
-            std::exception_ptr p = std::current_exception();
-            std::clog << (p ? p.__cxa_exception_type()->name() : "null")
-                      << std::endl;
+            log("Mysterious uncaught exception!");
         }
     }
 
@@ -126,22 +127,65 @@ private:
             return;
 
         collectConfig();
-        safeRunOnWorkerThread(
+        ::emergencyStop = false;
+        setState(STATE_READING);
+
+        runThen(
             [this]()
             {
                 auto& fluxSource = globalConfig().getFluxSource();
                 auto& decoder = globalConfig().getDecoder();
                 auto diskflux = readDiskCommand(*fluxSource, *decoder);
+            },
+            [this]()
+            {
+                setState(STATE_IDLE);
             });
     }
     W_SLOT(readDisk)
 
+private:
+    void emergencyStop()
+    {
+        ::emergencyStop = true;
+    }
+    W_SLOT(emergencyStop)
+
+    void setState(int state)
+    {
+        _stopWidget->setEnabled(state != STATE_IDLE);
+        _progressWidget->setEnabled(state != STATE_IDLE);
+        diskOperationsGroup->setEnabled(state == STATE_IDLE);
+        memoryOperationsGroup->setEnabled(state == STATE_IDLE);
+        driveWindow->setEnabled(state == STATE_IDLE);
+        formatWindow->setEnabled(state == STATE_IDLE);
+
+        _state = state;
+    }
+    W_SLOT(setState)
+
+private:
+    void runThen(
+        std::function<void()> workCb, std::function<void()> completionCb)
+    {
+        QFutureWatcher<void>* watcher = new QFutureWatcher<void>(this);
+        watcher->setFuture(safeRunOnWorkerThread(workCb));
+        connect(watcher, &QFutureWatcher<void>::finished, completionCb);
+        connect(watcher,
+            &QFutureWatcher<void>::finished,
+            watcher,
+            &QFutureWatcher<void>::deleteLater);
+    }
+
 private:
     DriveComponent* _driveComponent;
     FormatComponent* _formatComponent;
     FluxComponent* _fluxComponent;
     ImageComponent* _imageComponent;
+    QAbstractButton* _stopWidget;
     QProgressBar* _progressWidget;
+    std::shared_ptr<const DiskFlux> _currentDisk;
+    int _state;
 };
 W_OBJECT_IMPL(MainWindowImpl)
 
diff --git a/src/gui2/mainwindow.h b/src/gui2/mainwindow.h
index bfd5c675..87ef2baa 100644
--- a/src/gui2/mainwindow.h
+++ b/src/gui2/mainwindow.h
@@ -10,7 +10,5 @@ public:
 
 public:
     virtual void logMessage(std::shared_ptr<const AnyLogMessage> message) = 0;
-    virtual void setProgressBar(int progress) = 0;
-    virtual void finishedWithProgressBar() = 0;
     virtual void collectConfig() = 0;
 };
diff --git a/src/gui2/userinterface.ui b/src/gui2/userinterface.ui
index 74d277e6..fe775ddd 100644
--- a/src/gui2/userinterface.ui
+++ b/src/gui2/userinterface.ui
@@ -65,7 +65,7 @@
      </spacer>
     </item>
     <item row="6" column="3">
-     <widget class="QGroupBox" name="groupBox_2">
+     <widget class="QGroupBox" name="memoryOperationsGroup">
       <property name="sizePolicy">
        <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
         <horstretch>1</horstretch>
@@ -134,7 +134,10 @@
      </widget>
     </item>
     <item row="6" column="1">
-     <widget class="QGroupBox" name="groupBox">
+     <widget class="QGroupBox" name="diskOperationsGroup">
+      <property name="enabled">
+       <bool>true</bool>
+      </property>
       <property name="sizePolicy">
        <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
         <horstretch>1</horstretch>