diff --git a/src/cantor.cpp b/src/cantor.cpp
index 4f78e5a1..ff11203a 100644
--- a/src/cantor.cpp
+++ b/src/cantor.cpp
@@ -1,734 +1,729 @@
 /*
     This program is free software; you can redistribute it and/or
     modify it under the terms of the GNU General Public License
     as published by the Free Software Foundation; either version 2
     of the License, or (at your option) any later version.
 
     This program 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 General Public License for more details.
 
     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA  02110-1301, USA.
 
     ---
     Copyright (C) 2009 Alexander Rieder <alexanderrieder@gmail.com>
  */
 #include "cantor.h"
 
 #include <KActionCollection>
 #include <KConfigDialog>
 #include <KConfigGroup>
 #include <KMessageBox>
 #include <KShortcutsDialog>
 #include <KStandardAction>
 #include <KNS3/DownloadDialog>
 #include <KParts/ReadWritePart>
 #include <KRecentFilesAction>
 
 #include <QApplication>
 #include <QCloseEvent>
 #include <QDebug>
 #include <QDockWidget>
 #include <QDir>
 #include <QFileDialog>
 #include <QPushButton>
 #include <QRegularExpression>
 #include <QGraphicsView>
 
 #include "lib/backend.h"
 #include "lib/panelpluginhandler.h"
 #include "lib/panelplugin.h"
 #include "lib/worksheetaccess.h"
 
 #include "settings.h"
 #include "ui_settings.h"
 #include "backendchoosedialog.h"
 
 CantorShell::CantorShell() : KParts::MainWindow(), m_part(nullptr)
 {
     // set the shell's ui resource file
     setXMLFile(QLatin1String("cantor_shell.rc"));
 
     // then, setup our actions
     setupActions();
 
     createGUI(nullptr);
 
     m_tabWidget=new QTabWidget(this);
     m_tabWidget->setTabsClosable(true);
     m_tabWidget->setMovable(true);
     m_tabWidget->setDocumentMode(true);
     setCentralWidget(m_tabWidget);
 
     connect(m_tabWidget, SIGNAL(currentChanged(int)), this, SLOT(activateWorksheet(int)));
     connect(m_tabWidget, SIGNAL(tabCloseRequested(int)), this, SLOT(closeTab(int)));
 
     // apply the saved mainwindow settings, if any, and ask the mainwindow
     // to automatically save settings if changed: window size, toolbar
     // position, icon size, etc.
     setAutoSaveSettings();
 
     setDockOptions(QMainWindow::AnimatedDocks|QMainWindow::AllowTabbedDocks|QMainWindow::VerticalTabs);
 
     updateNewSubmenu();
 }
 
 CantorShell::~CantorShell()
 {
     if (m_recentProjectsAction)
         m_recentProjectsAction->saveEntries(KSharedConfig::openConfig()->group(QLatin1String("Recent Files")));
 
     if (!m_newBackendActions.isEmpty())
     {
         unplugActionList(QLatin1String("new_worksheet_with_backend_list"));
         qDeleteAll(m_newBackendActions);
         m_newBackendActions.clear();
     }
 
     unplugActionList(QLatin1String("view_show_panel_list"));
     qDeleteAll(m_panels);
     m_panels.clear();
 }
 
 void CantorShell::load(const QUrl &url)
 {
     if (!m_part||!m_part->url().isEmpty() || m_part->isModified() )
     {
         addWorksheet(QString());
         m_tabWidget->setCurrentIndex(m_parts.size()-1);
     }
     if (!m_part->openUrl( url ))
         closeTab(m_tabWidget->currentIndex());
     if (m_recentProjectsAction)
         m_recentProjectsAction->addUrl(url);
 
     updateWindowTitle(m_part->url().fileName());
 }
 
 void CantorShell::setupActions()
 {
     QAction* openNew = KStandardAction::openNew(this, SLOT(fileNew()), actionCollection());
     openNew->setPriority(QAction::LowPriority);
     QAction* open = KStandardAction::open(this, SLOT(fileOpen()), actionCollection());
     open->setPriority(QAction::LowPriority);
     m_recentProjectsAction = KStandardAction::openRecent(this, &CantorShell::load, actionCollection());
     m_recentProjectsAction->setPriority(QAction::LowPriority);
     m_recentProjectsAction->loadEntries(KSharedConfig::openConfig()->group(QLatin1String("Recent Files")));
 
     KStandardAction::close (this,  SLOT(closeTab()),  actionCollection());
 
     KStandardAction::quit(qApp, SLOT(closeAllWindows()), actionCollection());
 
     createStandardStatusBarAction();
     //setStandardToolBarMenuEnabled(true);
 
     KStandardAction::keyBindings(this, SLOT(optionsConfigureKeys()), actionCollection());
     KStandardAction::configureToolbars(this, SLOT(configureToolbars()), actionCollection());
 
     KStandardAction::preferences(this, SLOT(showSettings()), actionCollection());
 
     QAction * downloadExamples = new QAction(i18n("Download Example Worksheets"), actionCollection());
     downloadExamples->setIcon(QIcon::fromTheme(QLatin1String("get-hot-new-stuff")));
     actionCollection()->addAction(QLatin1String("file_example_download"),  downloadExamples);
     connect(downloadExamples, SIGNAL(triggered()), this,  SLOT(downloadExamples()));
 
     QAction * openExample =new QAction(i18n("&Open Example"), actionCollection());
     openExample->setIcon(QIcon::fromTheme(QLatin1String("document-open")));
     actionCollection()->addAction(QLatin1String("file_example_open"), openExample);
     connect(openExample, SIGNAL(triggered()), this, SLOT(openExample()));
 
     QAction* toPreviousTab = new QAction(i18n("Go to previous worksheet"), actionCollection());
     actionCollection()->addAction(QLatin1String("go_to_previous_tab"), toPreviousTab);
     actionCollection()->setDefaultShortcut(toPreviousTab, Qt::CTRL+Qt::Key_PageDown);
     connect(toPreviousTab, &QAction::triggered, toPreviousTab, [this](){
         const int index = m_tabWidget->currentIndex()-1;
         if (index >= 0)
             m_tabWidget->setCurrentIndex(index);
         else
             m_tabWidget->setCurrentIndex(m_tabWidget->count()-1);
     });
     addAction(toPreviousTab);
 
     QAction* toNextTab = new QAction(i18n("Go to next worksheet"), actionCollection());
     actionCollection()->addAction(QLatin1String("go_to_next_tab"), toNextTab);
     actionCollection()->setDefaultShortcut(toNextTab, Qt::CTRL+Qt::Key_PageUp);
     connect(toNextTab, &QAction::triggered, toNextTab, [this](){
         const int index = m_tabWidget->currentIndex()+1;
         if (index < m_tabWidget->count())
             m_tabWidget->setCurrentIndex(index);
         else
             m_tabWidget->setCurrentIndex(0);
     });
     addAction(toNextTab);
 }
 
 void CantorShell::saveProperties(KConfigGroup & /*config*/)
 {
     // the 'config' object points to the session managed
     // config file.  anything you write here will be available
     // later when this app is restored
 }
 
 void CantorShell::readProperties(const KConfigGroup & /*config*/)
 {
     // the 'config' object points to the session managed
     // config file.  this function is automatically called whenever
     // the app is being restored.  read in here whatever you wrote
     // in 'saveProperties'
 }
 
 /*!
  * called when one of the "new backend" action or the "New" action are called
  * adds a new worksheet with the backend assossiated with the called action
  * or opens the "Choose Backend" dialog, respectively.
  */
 void CantorShell::fileNew()
 {
     QAction* a = static_cast<QAction*>(sender());
     const QString& backendName = a->data().toString();
     if (!backendName.isEmpty())
     {
         addWorksheet(backendName);
         return;
     }
 
     //"New" action was called -> open the "Choose Backend" dialog.
     addWorksheet();
 }
 
 void CantorShell::optionsConfigureKeys()
 {
     KShortcutsDialog dlg( KShortcutsEditor::AllActions, KShortcutsEditor::LetterShortcutsDisallowed, this );
     dlg.addCollection( actionCollection(), i18n("Cantor") );
     if (m_part)
         dlg.addCollection( m_part->actionCollection(), i18n("Cantor") );
     dlg.configure( true );
 }
 
 void CantorShell::fileOpen()
 {
     // this slot is called whenever the File->Open menu is selected,
     // the Open shortcut is pressed (usually CTRL+O) or the Open toolbar
     // button is clicked
-    static const QString& worksheetFilter = i18n("Cantor Worksheet (*.cws)");
-    static const QString& notebookFilter = i18n("Jupyter Notebook (*.ipynb)");
-    QString filter;
-    if (m_previousFilter == notebookFilter)
-        filter = notebookFilter + QLatin1String(";;") + worksheetFilter;
-    else
-        filter = worksheetFilter + QLatin1String(";;") + notebookFilter;
-    QUrl url = QFileDialog::getOpenFileUrl(this, i18n("Open file"), QUrl(), filter, &m_previousFilter);
+    static const QString& filter = i18n("All supported files (*.cws *ipynb);;Cantor Worksheet (*.cws);;Jupyter Notebook (*.ipynb)");
+
+    QUrl url = QFileDialog::getOpenFileUrl(this, i18n("Open file"), QUrl(), filter);
 
     if (url.isEmpty() == false)
     {
         // About this function, the style guide
         // says that it should open a new window if the document is _not_
         // in its initial state.  This is what we do here..
         /*if ( m_part->url().isEmpty() && ! m_part->isModified() )
         {
             // we open the file in this window...
             load( url );
         }
         else
         {
             // we open the file in a new window...
             CantorShell* newWin = new CantorShell;
             newWin->load( url );
             newWin->show();
             }*/
         load( url );
     }
 }
 
 void CantorShell::addWorksheet()
 {
     bool hasBackend = false;
     for (auto* b : Cantor::Backend::availableBackends())
     {
         if(b->isEnabled())
         {
             hasBackend = true;
             break;
         }
     }
 
     if(hasBackend) //There is no point in asking for the backend, if no one is available
     {
         QString backend = Settings::self()->defaultBackend();
         if (backend.isEmpty())
         {
             QPointer<BackendChooseDialog> dlg=new BackendChooseDialog(this);
             if(dlg->exec())
             {
                 backend = dlg->backendName();
                 addWorksheet(backend);
             }
 
             delete dlg;
         }
         else
         {
             addWorksheet(backend);
         }
 
     }else
     {
         QTextBrowser *browser=new QTextBrowser(this);
         QString backendList=QLatin1String("<ul>");
         int backendListSize = 0;
         foreach(Cantor::Backend* b, Cantor::Backend::availableBackends())
         {
             if(!b->requirementsFullfilled()) //It's disabled because of missing dependencies, not because of some other reason(like eg. nullbackend)
             {
                 backendList+=QString::fromLatin1("<li>%1: <a href=\"%2\">%2</a></li>").arg(b->name(), b->url());
                 ++backendListSize;
             }
         }
         browser->setHtml(i18np("<h1>No Backend Found</h1>\n"             \
                                "<div>You could try:\n"                   \
                                "  <ul>"                                  \
                                "    <li>Changing the settings in the config dialog;</li>" \
                                "    <li>Installing packages for the following program:</li>" \
                                "     %2 "                                \
                                "  </ul> "                                 \
                                "</div> "
                               , "<h1>No Backend Found</h1>\n"             \
                                "<div>You could try:\n"                   \
                                "  <ul>"                                  \
                                "    <li>Changing the settings in the config dialog;</li>" \
                                "    <li>Installing packages for one of the following programs:</li>" \
                                "     %2 "                                \
                                "  </ul> "                                 \
                                "</div> "
                               , backendListSize, backendList
                               ));
 
         browser->setObjectName(QLatin1String("ErrorMessage"));
         m_tabWidget->addTab(browser, i18n("Error"));
     }
 }
 
 void CantorShell::addWorksheet(const QString& backendName)
 {
     static int sessionCount=1;
 
     // this routine will find and load our Part.  it finds the Part by
     // name which is a bad idea usually.. but it's alright in this
     // case since our Part is made for this Shell
     KPluginLoader loader(QLatin1String("cantorpart"));
     KPluginFactory* factory = loader.factory();
     if (factory)
     {
         if (!backendName.isEmpty())
         {
             Cantor::Backend* backend = Cantor::Backend::getBackend(backendName);
             if (!backend)
             {
                 KMessageBox::error(this, i18n("Backend %1 is not installed", backendName), i18n("Cantor"));
                 return;
             }
             else
             {
                 if (!backend->isEnabled())
                 {
                     KMessageBox::error(this, i18n("%1 backend installed, but inactive. Please check installation and Cantor settings", backendName), i18n("Cantor"));
                     return;
                 }
             }
         }
 
         // now that the Part is loaded, we cast it to a Part to get our hands on it
         KParts::ReadWritePart* part = factory->create<KParts::ReadWritePart>(m_tabWidget, QVariantList()<<backendName);
         if (part)
         {
             connect(part, SIGNAL(setCaption(QString,QIcon)), this, SLOT(setTabCaption(QString,QIcon)));
             connect(part, SIGNAL(worksheetSave(QUrl)), this, SLOT(onWorksheetSave(QUrl)));
             m_parts.append(part);
 
             int tab = m_tabWidget->addTab(part->widget(), i18n("Session %1", sessionCount++));
             m_tabWidget->setCurrentIndex(tab);
             // Setting focus on worksheet view, because Qt clear focus of added widget inside addTab
             // This fix https://bugs.kde.org/show_bug.cgi?id=395976
             part->widget()->findChild<QGraphicsView*>()->setFocus();
 
             // Force run updateCaption for getting proper backend icon
             QMetaObject::invokeMethod(part, "updateCaption");
         }
         else
         {
             qDebug()<<"error creating part ";
         }
     }
     else
     {
         // if we couldn't find our Part, we exit since the Shell by
         // itself can't do anything useful
         KMessageBox::error(this, i18n("Failed to find the Cantor Part with error %1", loader.errorString()));
         qApp->quit();
         // we return here, cause qApp->quit() only means "exit the
         // next time we enter the event loop...
         return;
     }
 
 }
 
 void CantorShell::activateWorksheet(int index)
 {
     QObject* pluginHandler=m_part->findChild<QObject*>(QLatin1String("PanelPluginHandler"));
     if (pluginHandler)
         disconnect(pluginHandler,SIGNAL(pluginsChanged()), this, SLOT(updatePanel()));
 
     // Save part state before change worksheet
     if (m_part)
     {
         QStringList visiblePanelNames;
         foreach (QDockWidget* doc, m_panels)
         {
             if (doc->widget() && doc->widget()->isVisible())
                 visiblePanelNames << doc->objectName();
         }
         m_pluginsVisibility[m_part] = visiblePanelNames;
     }
 
     m_part=findPart(m_tabWidget->widget(index));
     if(m_part)
     {
         createGUI(m_part);
 
         updateWindowTitle(m_part->url().fileName());
         QObject* pluginHandler=m_part->findChild<QObject*>(QLatin1String("PanelPluginHandler"));
         connect(pluginHandler, SIGNAL(pluginsChanged()), this, SLOT(updatePanel()));
         updatePanel();
     }
     else
         qDebug()<<"selected part doesn't exist";
 
     m_tabWidget->setCurrentIndex(index);
 }
 
 void CantorShell::setTabCaption(const QString& caption, const QIcon& icon)
 {
     KParts::ReadWritePart* part=dynamic_cast<KParts::ReadWritePart*>(sender());
     if (part)
     {
         if (!caption.isEmpty())
             m_tabWidget->setTabText(m_tabWidget->indexOf(part->widget()), caption);
         m_tabWidget->setTabIcon(m_tabWidget->indexOf(part->widget()), icon);
     }
 }
 
 void CantorShell::updateWindowTitle(const QString& fileName)
 {
     QFileInfo info(fileName);
     setWindowTitle(info.baseName());
 }
 
 void CantorShell::closeTab(int index)
 {
     if (!reallyClose(false))
     {
         return;
     }
 
     QWidget* widget = nullptr;
     if (index >= 0)
     {
         widget = m_tabWidget->widget(index);
     }
     else if (m_part)
     {
         widget = m_part->widget();
     }
 
     if (!widget)
     {
         qWarning() << "Could not find widget by tab index" << index;
         return;
     }
 
 
     m_tabWidget->removeTab(index);
 
     if(widget->objectName()==QLatin1String("ErrorMessage"))
     {
         widget->deleteLater();
     }else
     {
         KParts::ReadWritePart* part= findPart(widget);
         if(part)
         {
             m_parts.removeAll(part);
             m_pluginsVisibility.remove(part);
             delete part;
         }
     }
 
     if (m_tabWidget->count() == 0)
         setCaption(QString());
     updatePanel();
 }
 
 bool CantorShell::reallyClose(bool checkAllParts) {
     if(checkAllParts && m_parts.count() > 1) {
         bool modified = false;
         foreach( KParts::ReadWritePart* const part, m_parts)
         {
             if(part->isModified()) {
                 modified = true;
                 break;
             }
         }
         if(!modified) return true;
         int want_save = KMessageBox::warningYesNo( this,
             i18n("Multiple unsaved Worksheets are opened. Do you want to close them?"),
             i18n("Close Cantor"));
         switch (want_save) {
             case KMessageBox::Yes:
                 return true;
             case KMessageBox::No:
                 return false;
         }
     }
     if (m_part && m_part->isModified() ) {
         int want_save = KMessageBox::warningYesNoCancel( this,
             i18n("The current project has been modified. Do you want to save it?"),
             i18n("Save Project"));
         switch (want_save) {
             case KMessageBox::Yes:
                 m_part->save();
                 if(m_part->waitSaveComplete()) {
                     return true;
                 } else {
                     m_part->setModified(true);
                     return false;
                 }
             case KMessageBox::Cancel:
                 return false;
             case KMessageBox::No:
                 return true;
         }
     }
     return true;
 }
 
 void CantorShell::closeEvent(QCloseEvent* event) {
     if(!reallyClose()) {
         event->ignore();
     } else {
         KParts::MainWindow::closeEvent(event);
     }
 }
 
 void CantorShell::showSettings()
 {
     KConfigDialog *dialog = new KConfigDialog(this,  QLatin1String("settings"), Settings::self());
     QWidget *generalSettings = new QWidget;
     Ui::SettingsBase base;
     base.setupUi(generalSettings);
     base.kcfg_DefaultBackend->addItems(Cantor::Backend::listAvailableBackends());
 
     dialog->addPage(generalSettings, i18n("General"), QLatin1String("preferences-other"));
     foreach(Cantor::Backend* backend, Cantor::Backend::availableBackends())
     {
         if (backend->config()) //It has something to configure, so add it to the dialog
             dialog->addPage(backend->settingsWidget(dialog), backend->config(), backend->name(),  backend->icon());
     }
 
     dialog->show();
 }
 
 void CantorShell::downloadExamples()
 {
     KNS3::DownloadDialog dialog;
     dialog.exec();
     foreach (const KNS3::Entry& e,  dialog.changedEntries())
     {
         qDebug() << "Changed Entry: " << e.name();
     }
 }
 
 void CantorShell::openExample()
 {
     QString dir = QStandardPaths::writableLocation(QStandardPaths::DataLocation) + QLatin1String("/examples");
     if (dir.isEmpty()) return;
     QDir().mkpath(dir);
 
     QStringList files=QDir(dir).entryList(QDir::Files);
     QPointer<QDialog> dlg=new QDialog(this);
     QListWidget* list=new QListWidget(dlg);
     foreach(const QString& file, files)
     {
         QString name=file;
         name.remove(QRegularExpression(QStringLiteral("-.*\\.hotstuff-access$")));
         list->addItem(name);
     }
 
     QVBoxLayout *mainLayout = new QVBoxLayout;
     dlg->setLayout(mainLayout);
     mainLayout->addWidget(list);
 
     QDialogButtonBox *buttonBox = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel);
 
     mainLayout->addWidget(buttonBox);
 
     buttonBox->button(QDialogButtonBox::Ok)->setIcon(QApplication::style()->standardIcon(QStyle::SP_DialogOkButton));
     buttonBox->button(QDialogButtonBox::Cancel)->setIcon(QApplication::style()->standardIcon(QStyle::SP_DialogCancelButton));
 
     connect(buttonBox, SIGNAL(accepted()), dlg, SLOT(accept()) );
     connect(buttonBox, SIGNAL(rejected()), dlg, SLOT(reject()) );
 
     if (dlg->exec()==QDialog::Accepted&&list->currentRow()>=0)
     {
         const QString& selectedFile=files[list->currentRow()];
         QUrl url = QUrl::fromLocalFile(QDir(dir).absoluteFilePath(selectedFile));
 
         qDebug()<<"loading file "<<url;
         load(url);
     }
 
     delete dlg;
 }
 
 KParts::ReadWritePart* CantorShell::findPart(QWidget* widget)
 {
     foreach( KParts::ReadWritePart* const part, m_parts)
     {
         if(part->widget()==widget)
             return part;
     }
     return nullptr;
 }
 
 void CantorShell::updatePanel()
 {
     unplugActionList(QLatin1String("view_show_panel_list"));
 
     //remove all of the previous panels (but do not delete the widgets)
     foreach(QDockWidget* dock, m_panels)
     {
         QWidget* widget=dock->widget();
         if(widget!=nullptr)
         {
             widget->setParent(this);
             widget->hide();
         }
         dock->deleteLater();
     }
     m_panels.clear();
 
     QList<QAction*> panelActions;
 
     Cantor::PanelPluginHandler* handler=m_part->findChild<Cantor::PanelPluginHandler*>(QLatin1String("PanelPluginHandler"));
     if(!handler)
     {
         qDebug()<<"no PanelPluginHandle found for this part";
         return;
     }
 
     QDockWidget* last=nullptr;
 
     QList<Cantor::PanelPlugin*> plugins=handler->plugins();
     const bool isNewWorksheet = !m_pluginsVisibility.contains(m_part);
     foreach(Cantor::PanelPlugin* plugin, plugins)
     {
         if(plugin==nullptr)
         {
             qDebug()<<"somethings wrong";
             continue;
         }
 
         qDebug()<<"adding panel for "<<plugin->name();
         plugin->setParentWidget(this);
 
         QDockWidget* docker=new QDockWidget(plugin->name(), this);
         docker->setObjectName(plugin->name());
         docker->setWidget(plugin->widget());
         addDockWidget ( Qt::RightDockWidgetArea,  docker );
 
         // Set visibility for dock from saved info
         if (isNewWorksheet)
         {
             if (plugin->showOnStartup())
                 docker->show();
             else
                 docker->hide();
         }
         else
         {
             if (m_pluginsVisibility[m_part].contains(plugin->name()))
                 docker->show();
             else
                 docker->hide();
         }
 
         if(last!=nullptr)
             tabifyDockWidget(last, docker);
         last=docker;
 
         connect(plugin, &Cantor::PanelPlugin::visibilityRequested, this, &CantorShell::pluginVisibilityRequested);
 
         m_panels.append(docker);
 
         //Create the action to show/hide this panel
         panelActions<<docker->toggleViewAction();
 
     }
 
     plugActionList(QLatin1String("view_show_panel_list"), panelActions);
 
     updateNewSubmenu();
 }
 
 void CantorShell::updateNewSubmenu()
 {
     unplugActionList(QLatin1String("new_worksheet_with_backend_list"));
     qDeleteAll(m_newBackendActions);
     m_newBackendActions.clear();
 
     foreach (Cantor::Backend* backend, Cantor::Backend::availableBackends())
     {
         if (!backend->isEnabled())
             continue;
         QAction * action = new QAction(QIcon::fromTheme(backend->icon()), backend->name(), nullptr);
         action->setData(backend->name());
         connect(action, SIGNAL(triggered()), this, SLOT(fileNew()));
         m_newBackendActions << action;
     }
     plugActionList(QLatin1String("new_worksheet_with_backend_list"), m_newBackendActions);
 }
 
 Cantor::WorksheetAccessInterface* CantorShell::currentWorksheetAccessInterface()
 {
     Cantor::WorksheetAccessInterface* wa=m_part->findChild<Cantor::WorksheetAccessInterface*>(Cantor::WorksheetAccessInterface::Name);
 
     if (!wa)
         qDebug()<<"failed to access worksheet access interface for current part";
 
     return wa;
 }
 
 void CantorShell::pluginVisibilityRequested()
 {
     Cantor::PanelPlugin* plugin = static_cast<Cantor::PanelPlugin*>(sender());
     for (QDockWidget* docker: m_panels)
     {
         if (plugin->name() == docker->windowTitle())
         {
             if (docker->isHidden())
                 docker->show();
             docker->raise();
         }
     }
 }
 
 void CantorShell::onWorksheetSave(const QUrl& url)
 {
     if (m_recentProjectsAction)
         m_recentProjectsAction->addUrl(url);
 
     updateWindowTitle(m_part->url().fileName());
 }
diff --git a/src/cantor.h b/src/cantor.h
index 72e80dfb..52cb8fbe 100644
--- a/src/cantor.h
+++ b/src/cantor.h
@@ -1,124 +1,122 @@
 /*
     Copyright (C) 2009 Alexander Rieder <alexanderrieder@gmail.com>
 
     This program is free software; you can redistribute it and/or
     modify it under the terms of the GNU General Public License
     as published by the Free Software Foundation; either version 2
     of the License, or (at your option) any later version.
 
     This program 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 General Public License for more details.
 
     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA  02110-1301, USA.
  */
 
 
 #ifndef CANTOR_H
 #define CANTOR_H
 
 #include <QObject>
 #include <KParts/MainWindow>
 
 #include <QList>
 #include <QStringList>
 #include <QMap>
 
 class QTabWidget;
 class KTextEdit;
 class KRecentFilesAction;
 
 namespace Cantor{
 class WorksheetAccessInterface;
 }
 
 namespace KParts{
     class ReadWritePart;
 }
 
 /**
  * This is the application "Shell".  It has a menubar, toolbar, and
  * statusbar but relies on the "Part" to do all the real work.
  */
 class CantorShell : public KParts::MainWindow
 {
     Q_OBJECT
 public:
     /**
      * Default Constructor
      */
     CantorShell();
 
     /**
      * Default Destructor
      */
     ~CantorShell() override;
 
     Cantor::WorksheetAccessInterface* currentWorksheetAccessInterface();
     void addWorksheet();
 
 protected:
     /**
      * This method is called when it is time for the app to save its
      * properties for session management purposes.
      */
     void saveProperties(KConfigGroup &) override;
 
     /**
      * This method is called when this app is restored.  The KConfig
      * object points to the session management config file that was saved
      * with @ref saveProperties
      */
     void readProperties(const KConfigGroup &) override;
 
 public Q_SLOTS:
     void addWorksheet(const QString& backendName);
     /// Use this method/slot to load whatever file/URL you have
     void load(const QUrl& url);
 
 private Q_SLOTS:
     void fileNew();
     void fileOpen();
     void onWorksheetSave(const QUrl& url);
     void optionsConfigureKeys();
 
     void activateWorksheet(int index);
 
     void setTabCaption(const QString& tab, const QIcon& icon);
     void closeTab(int index = -1);
 
     void showSettings();
 
     void downloadExamples();
     void openExample();
 
     void updatePanel();
     void updateNewSubmenu();
 
     void pluginVisibilityRequested();
 
 private:
     void setupActions();
     void closeEvent(QCloseEvent*) override;
     bool reallyClose(bool checkAllParts = true);
     void updateWindowTitle(const QString& fileName);
     KParts::ReadWritePart* findPart(QWidget* widget);
 
 private:
     QMap<KParts::ReadWritePart*, QStringList> m_pluginsVisibility;
     QList<KParts::ReadWritePart *> m_parts;
     KParts::ReadWritePart* m_part;
     QTabWidget* m_tabWidget;
     QList<QDockWidget*> m_panels;
     QList<QAction*> m_newBackendActions;
     QDockWidget* m_helpDocker;
     KRecentFilesAction* m_recentProjectsAction;
-    // For better UX: set previous used filter in "Open" action as default filter
-    QString m_previousFilter;
 };
 
 #endif // CANTOR_H