diff --git a/src/backends/R/rsession.cpp b/src/backends/R/rsession.cpp
index 652c23f3..aed4841f 100644
--- a/src/backends/R/rsession.cpp
+++ b/src/backends/R/rsession.cpp
@@ -1,191 +1,191 @@
 /*
     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>
     Copyright (C) 2018 Alexander Semke <alexander.semke@web.de>
  */
 
 #include "rsession.h"
 #include "rexpression.h"
 #include "rcompletionobject.h"
 #include "rhighlighter.h"
 #include "rvariablemodel.h"
 #include <defaultvariablemodel.h>
 
 #include <QTimer>
 #include <QDebug>
 #include <KProcess>
 
 #ifndef Q_OS_WIN
 #include <signal.h>
 #endif
 
-RSession::RSession(Cantor::Backend* backend) : Session(backend, new RVariableModel(this)),
+RSession::RSession(Cantor::Backend* backend) : Session(backend),
 m_process(nullptr),
 m_rServer(nullptr)
 {
+    setVariableModel(new RVariableModel(this));
 }
 
 RSession::~RSession()
 {
     if (m_process)
         m_process->terminate();
 }
 
 void RSession::login()
 {
     qDebug()<<"login";
     emit loginStarted();
 
     if(m_process)
         m_process->deleteLater();
 
     m_process = new QProcess(this);
     m_process->start(QStandardPaths::findExecutable(QLatin1String("cantor_rserver")));
 
     m_process->waitForStarted();
     m_process->waitForReadyRead();
     qDebug()<<m_process->readAllStandardOutput();
 
     m_rServer = new org::kde::Cantor::R(QString::fromLatin1("org.kde.Cantor.R-%1").arg(m_process->pid()),  QLatin1String("/"), QDBusConnection::sessionBus(), this);
 
     connect(m_rServer, SIGNAL(statusChanged(int)), this, SLOT(serverChangedStatus(int)));
 
     changeStatus(Session::Done);
     emit loginDone();
     qDebug()<<"login done";
 }
 
 void RSession::logout()
 {
     qDebug()<<"logout";
     m_process->terminate();
 
     RVariableModel* model = static_cast<RVariableModel*>(variableModel());
     model->clearVariables();
     model->clearFunctions();
     emit symbolsChanged();
 
     changeStatus(Status::Disable);
 }
 
 void RSession::interrupt()
 {
     if(!expressionQueue().isEmpty())
     {
         qDebug()<<"interrupting " << expressionQueue().first()->command();
         if(m_process->state() != QProcess::NotRunning)
         {
 #ifndef Q_OS_WIN
             const int pid=m_process->pid();
             kill(pid, SIGINT);
 #else
             ; //TODO: interrupt the process on windows
 #endif
         }
        foreach (Cantor::Expression* expression, expressionQueue())
             expression->setStatus(Cantor::Expression::Interrupted);
         expressionQueue().clear();
 
         qDebug()<<"done interrupting";
     }
 
     changeStatus(Cantor::Session::Done);
 }
 
 Cantor::Expression* RSession::evaluateExpression(const QString& cmd, Cantor::Expression::FinishingBehavior behave, bool internal)
 {
     qDebug()<<"evaluating: "<<cmd;
     RExpression* expr=new RExpression(this, internal);
     expr->setFinishingBehavior(behave);
     expr->setCommand(cmd);
 
     expr->evaluate();
 
     return expr;
 }
 
 Cantor::CompletionObject* RSession::completionFor(const QString& command, int index)
 {
     RCompletionObject *cmp=new RCompletionObject(command, index, this);
     connect(m_rServer,SIGNAL(completionFinished(QString,QStringList)),cmp,SLOT(receiveCompletions(QString,QStringList)));
     connect(cmp,SIGNAL(requestCompletion(QString)),m_rServer,SLOT(completeCommand(QString)));
     return cmp;
 }
 
 QSyntaxHighlighter* RSession::syntaxHighlighter(QObject* parent)
 {
     RHighlighter *h=new RHighlighter(parent);
     RVariableModel* model = static_cast<RVariableModel*>(variableModel());
     connect(model, &Cantor::DefaultVariableModel::variablesAdded, h, &RHighlighter::addUserVariable);
     connect(model, &Cantor::DefaultVariableModel::variablesRemoved, h, &RHighlighter::removeUserVariable);
     connect(model, &Cantor::DefaultVariableModel::functionsAdded, h, &RHighlighter::addUserFunction);
     connect(model, &Cantor::DefaultVariableModel::functionsRemoved, h, &RHighlighter::removeUserFunction);
     return h;
 }
 
 void RSession::serverChangedStatus(int status)
 {
     qDebug()<<"changed status to "<<status;
     if(status==0)
     {
         if(!expressionQueue().isEmpty())
         {
             RExpression* expr = static_cast<RExpression*>(expressionQueue().first());
             qDebug()<<"done running "<<expr<<" "<<expr->command();
         }
-
-       finishFirstExpression();
+        finishFirstExpression();
     }
     else
         changeStatus(Cantor::Session::Running);
 }
 
 void RSession::runFirstExpression()
 {
     if (expressionQueue().isEmpty())
         return;
 
     disconnect(m_rServer,  SIGNAL(expressionFinished(int,QString)),  nullptr,  nullptr);
     disconnect(m_rServer, SIGNAL(inputRequested(QString)), nullptr, nullptr);
     disconnect(m_rServer, SIGNAL(showFilesNeeded(QStringList)), nullptr, nullptr);
     qDebug()<<"size: "<<expressionQueue().size();
     RExpression* expr = static_cast<RExpression*>(expressionQueue().first());
     qDebug()<<"running expression: "<<expr->command();
 
     connect(m_rServer, SIGNAL(expressionFinished(int,QString)), expr, SLOT(finished(int,QString)));
     connect(m_rServer, SIGNAL(inputRequested(QString)), expr, SIGNAL(needsAdditionalInformation(QString)));
     connect(m_rServer, SIGNAL(showFilesNeeded(QStringList)), expr, SLOT(showFilesAsResult(QStringList)));
 
     expr->setStatus(Cantor::Expression::Computing);
     m_rServer->runCommand(expr->command());
 }
 
 void RSession::sendInputToServer(const QString& input)
 {
     QString s=input;
     if(!input.endsWith(QLatin1Char('\n')))
         s+=QLatin1Char('\n');
     m_rServer->answerRequest(s);
 }
 
 void RSession::updateSymbols(const RVariableModel* model)
 {
     disconnect(m_rServer, SIGNAL(symbolList(QStringList,QStringList,QStringList)));
     connect(m_rServer, SIGNAL(symbolList(QStringList,QStringList,QStringList)), model, SLOT(parseResult(QStringList,QStringList,QStringList)));
     m_rServer->listSymbols();
 }
diff --git a/src/backends/maxima/maximasession.cpp b/src/backends/maxima/maximasession.cpp
index 54fc789d..ddfbccd1 100644
--- a/src/backends/maxima/maximasession.cpp
+++ b/src/backends/maxima/maximasession.cpp
@@ -1,332 +1,333 @@
 /*
     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) 2009-2012 Alexander Rieder <alexanderrieder@gmail.com>
     Copyright (C) 2017-2018 Alexander Semke (alexander.semke@web.de)
  */
 
 #include "maximasession.h"
 #include "maximaexpression.h"
 #include "maximacompletionobject.h"
 #include "maximasyntaxhelpobject.h"
 #include "maximahighlighter.h"
 #include "maximavariablemodel.h"
 #include "result.h"
 #include "settings.h"
 
 #include <QDebug>
 #include <QProcess>
 #include <QTimer>
 
 #include <KMessageBox>
 #include <KLocalizedString>
 
 #ifndef Q_OS_WIN
 #include <signal.h>
 #endif
 
 
 //NOTE: the \\s in the expressions is needed, because Maxima seems to sometimes insert newlines/spaces between the letters
 //maybe this is caused by some behaviour if the Prompt is split into multiple "readStdout" calls
 //the Expressions are encapsulated in () to allow capturing for the text
 const QRegExp MaximaSession::MaximaOutputPrompt=QRegExp(QLatin1String("(\\(\\s*%\\s*o\\s*[0-9\\s]*\\))")); //Text, maxima outputs, before any output
 const QRegExp MaximaSession::MaximaInputPrompt = QRegExp(QLatin1String("(\\(\\s*%\\s*i\\s*[0-9\\s]*\\))"));
 
 
-MaximaSession::MaximaSession( Cantor::Backend* backend ) : Session(backend, new MaximaVariableModel(this)),
+MaximaSession::MaximaSession( Cantor::Backend* backend ) : Session(backend),
     m_process(nullptr),
     m_justRestarted(false)
 {
+    setVariableModel(new MaximaVariableModel(this));
 }
 
 void MaximaSession::login()
 {
     qDebug()<<"login";
 
     if (m_process)
         return; //TODO: why do we call login() again?!?
 
     emit loginStarted();
     QStringList arguments;
     arguments << QLatin1String("--quiet"); //Suppress Maxima start-up message
     const QString initFile = QStandardPaths::locate(QStandardPaths::GenericDataLocation, QLatin1String("cantor/maximabackend/cantor-initmaxima.lisp"));
     arguments << QLatin1String("--init-lisp=") + initFile; //Set the name of the Lisp initialization file
 
     m_process = new QProcess(this);
     m_process->start(MaximaSettings::self()->path().toLocalFile(), arguments);
     m_process->waitForStarted();
 
     QString input;
     // Wait until first maxima prompt
     while (!input.contains(QLatin1String("</cantor-prompt>")))
     {
         m_process->waitForReadyRead();
         input += QString::fromLatin1(m_process->readAllStandardOutput());
         qDebug() << input;
     }
 
     connect(m_process, SIGNAL(finished(int,QProcess::ExitStatus)), this, SLOT(restartMaxima()));
     connect(m_process, SIGNAL(readyReadStandardOutput()), this, SLOT(readStdOut()));
     connect(m_process, SIGNAL(readyReadStandardError()), this, SLOT(readStdErr()));
     connect(m_process, SIGNAL(error(QProcess::ProcessError)), this, SLOT(reportProcessError(QProcess::ProcessError)));
 
     if(!MaximaSettings::self()->autorunScripts().isEmpty()){
         QString autorunScripts = MaximaSettings::self()->autorunScripts().join(QLatin1String(";"));
         autorunScripts.append(QLatin1String(";kill(labels)")); // Reset labels after running autorun scripts
         evaluateExpression(autorunScripts, MaximaExpression::DeleteOnFinish, true);
         forceVariableUpdate();
     }
 
     changeStatus(Session::Done);
     emit loginDone();
     qDebug()<<"login done";
 }
 
 void MaximaSession::logout()
 {
     qDebug()<<"logout";
 
     if(!m_process)
         return;
 
     disconnect(m_process, nullptr, this, nullptr);
 
 //     if(status()==Cantor::Session::Running)
         //TODO: terminate the running expressions first
 
     write(QLatin1String("quit();\n"));
     qDebug()<<"waiting for maxima to finish";
     m_process->waitForFinished();
     qDebug()<<"maxima exit finished";
 
     if(m_process->state() != QProcess::NotRunning)
     {
         m_process->kill();
         qDebug()<<"maxima still running, process kill enforced";
     }
 
     expressionQueue().clear();
     delete m_process;
     m_process = nullptr;
     MaximaVariableModel* model = static_cast<MaximaVariableModel*>(variableModel());
     model->clearVariables();
     model->clearFunctions();
 
     changeStatus(Status::Disable);
 
     qDebug()<<"logout done";
 }
 
 Cantor::Expression* MaximaSession::evaluateExpression(const QString& cmd, Cantor::Expression::FinishingBehavior behave, bool internal)
 {
     qDebug() << "evaluating: " << cmd;
     MaximaExpression* expr = new MaximaExpression(this, internal);
     expr->setFinishingBehavior(behave);
     expr->setCommand(cmd);
     expr->evaluate();
 
     return expr;
 }
 
 void MaximaSession::readStdErr()
 {
    qDebug()<<"reading stdErr";
    if (!m_process)
        return;
    QString out=QLatin1String(m_process->readAllStandardError());
 
    if(expressionQueue().size()>0)
    {
        MaximaExpression* expr = static_cast<MaximaExpression*>(expressionQueue().first());
        expr->parseError(out);
    }
 }
 
 void MaximaSession::readStdOut()
 {
     QString out = QLatin1String(m_process->readAllStandardOutput());
     m_cache += out;
 
     //collect the multi-line output until Maxima has finished the calculation and returns a new promt
     if ( !out.contains(QLatin1String("</cantor-prompt>")) )
         return;
 
     if(expressionQueue().isEmpty())
     {
         //queue is empty, interrupt was called, nothing to do here
         qDebug()<<m_cache;
         m_cache.clear();
         return;
     }
 
     MaximaExpression* expr = static_cast<MaximaExpression*>(expressionQueue().first());
     if (!expr)
         return; //should never happen
 
     qDebug()<<"output: " << m_cache;
     expr->parseOutput(m_cache);
     m_cache.clear();
 }
 
 void MaximaSession::reportProcessError(QProcess::ProcessError e)
 {
     qDebug()<<"process error"<<e;
     if(e==QProcess::FailedToStart)
     {
         changeStatus(Cantor::Session::Done);
         emit error(i18n("Failed to start Maxima"));
     }
 }
 
 void MaximaSession::currentExpressionChangedStatus(Cantor::Expression::Status status)
 {
     Cantor::Expression* expression = expressionQueue().first();
     const QString& cmd = expression->command();
     qDebug() << "expression status changed: command = " << expression->command() << ", status = " << status;
 
     switch (status)
     {
     case Cantor::Expression::Done:
     case Cantor::Expression::Error:
         qDebug()<<"################################## EXPRESSION END ###############################################";
         disconnect(expression, SIGNAL(statusChanged(Cantor::Expression::Status)),
             this, SLOT(currentExpressionChangedStatus(Cantor::Expression::Status)));
 
         finishFirstExpression();
         break;
 
     default:
         break;
     }
 }
 
 void MaximaSession::runFirstExpression()
 {
     qDebug()<<"running next expression";
     if (!m_process)
         return;
 
     if(!expressionQueue().isEmpty())
     {
         MaximaExpression* expr = static_cast<MaximaExpression*>(expressionQueue().first());
         QString command=expr->internalCommand();
         connect(expr, SIGNAL(statusChanged(Cantor::Expression::Status)), this, SLOT(currentExpressionChangedStatus(Cantor::Expression::Status)));
 
         expr->setStatus(Cantor::Expression::Computing);
         if(command.isEmpty())
         {
             qDebug()<<"empty command";
             expr->forceDone();
         }
         else
         {
             m_cache.clear();
             write(command + QLatin1Char('\n'));
         }
     }
 }
 
 void MaximaSession::interrupt()
 {
     if(!expressionQueue().isEmpty())
     {
         qDebug()<<"interrupting " << expressionQueue().first()->command();
         if(m_process->state() != QProcess::NotRunning)
         {
 #ifndef Q_OS_WIN
             const int pid=m_process->pid();
             kill(pid, SIGINT);
 #else
             ; //TODO: interrupt the process on windows
 #endif
         }
        foreach (Cantor::Expression* expression, expressionQueue())
             expression->setStatus(Cantor::Expression::Interrupted);
         expressionQueue().clear();
 
         qDebug()<<"done interrupting";
     }
 
     changeStatus(Cantor::Session::Done);
     m_cache.clear();
 }
 
 void MaximaSession::sendInputToProcess(const QString& input)
 {
     write(input);
 }
 
 void MaximaSession::restartMaxima()
 {
     qDebug()<<"restarting maxima cooldown: "<<m_justRestarted;
 
     if(!m_justRestarted)
     {
         emit error(i18n("Maxima crashed. restarting..."));
         //remove the command that caused maxima to crash (to avoid infinite loops)
         if(!expressionQueue().isEmpty())
             expressionQueue().removeFirst();
 
         m_justRestarted=true;
         QTimer::singleShot(1000, this, SLOT(restartsCooledDown()));
 
         disconnect(m_process, SIGNAL(finished(int,QProcess::ExitStatus)), this, SLOT(restartMaxima()));
         login();
     }else
     {
         if(!expressionQueue().isEmpty())
             expressionQueue().removeFirst();
         KMessageBox::error(nullptr, i18n("Maxima crashed twice within a short time. Stopping to try starting"), i18n("Error - Cantor"));
     }
 }
 
 void MaximaSession::restartsCooledDown()
 {
     qDebug()<<"maxima restart cooldown";
     m_justRestarted=false;
 }
 
 void MaximaSession::setTypesettingEnabled(bool enable)
 {
     //we use the lisp command to set the variable, as those commands
     //don't mess with the labels and history
     const QString& val=QLatin1String((enable==true ? "t":"nil"));
     evaluateExpression(QString::fromLatin1(":lisp(setf $display2d %1)").arg(val), Cantor::Expression::DeleteOnFinish, true);
 
     Cantor::Session::setTypesettingEnabled(enable);
 }
 
 Cantor::CompletionObject* MaximaSession::completionFor(const QString& command, int index)
 {
     return new MaximaCompletionObject(command, index, this);
 }
 
 Cantor::SyntaxHelpObject* MaximaSession::syntaxHelpFor(const QString& command)
 {
     return new MaximaSyntaxHelpObject(command, this);
 }
 
 QSyntaxHighlighter* MaximaSession::syntaxHighlighter(QObject* parent)
 {
     return new MaximaHighlighter(parent, this);
 }
 
 void MaximaSession::write(const QString& exp) {
     qDebug()<<"################################## EXPRESSION START ###############################################";
     qDebug()<<"sending expression to maxima process: " << exp;
     m_process->write(exp.toUtf8());
 }
diff --git a/src/backends/octave/octavesession.cpp b/src/backends/octave/octavesession.cpp
index 04cb18ce..f6eb59b6 100644
--- a/src/backends/octave/octavesession.cpp
+++ b/src/backends/octave/octavesession.cpp
@@ -1,374 +1,376 @@
 /*
     Copyright (C) 2010 Miha Čančula <miha.cancula@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.
 */
 
 #include "octavesession.h"
 #include "octaveexpression.h"
 #include "octavecompletionobject.h"
 #include "octavesyntaxhelpobject.h"
 #include "octavehighlighter.h"
 #include "result.h"
 #include "textresult.h"
 
 #include "settings.h"
 #include "octave-backend-config.h"
 #include "octavehighlighter.h"
 
 #include <KProcess>
 #include <KDirWatch>
 #include <KLocalizedString>
 
 #include <QTimer>
 #include <QFile>
 
 #ifndef Q_OS_WIN
 #include <signal.h>
 #endif
 
 #include "octavevariablemodel.h"
 
 const QRegExp OctaveSession::PROMPT_UNCHANGEABLE_COMMAND = QRegExp(QLatin1String("(,|;)+"));
 
-OctaveSession::OctaveSession ( Cantor::Backend* backend ) : Session ( backend, new OctaveVariableModel(this) ),
+OctaveSession::OctaveSession ( Cantor::Backend* backend ) : Session ( backend),
 m_process(nullptr),
 m_prompt(QLatin1String("CANTOR_OCTAVE_BACKEND_PROMPT:([0-9]+)> ")),
 m_subprompt(QLatin1String("CANTOR_OCTAVE_BACKEND_SUBPROMPT:([0-9]+)> ")),
 m_previousPromptNumber(1),
 m_watch(nullptr),
 m_syntaxError(false)
 {
+    setVariableModel(new OctaveVariableModel(this));
     qDebug() << octaveScriptInstallDir;
 }
 
 void OctaveSession::login()
 {
     qDebug() << "login";
     emit loginStarted();
 
     m_process = new KProcess ( this );
     QStringList args;
     args << QLatin1String("--silent");
     args << QLatin1String("--interactive");
     args << QLatin1String("--persist");
 
     // Setting prompt and subprompt
     args << QLatin1String("--eval");
     args << QLatin1String("PS1('CANTOR_OCTAVE_BACKEND_PROMPT:\\#> ');");
     args << QLatin1String("--eval");
     args << QLatin1String("PS2('CANTOR_OCTAVE_BACKEND_SUBPROMPT:\\#> ');");
 
     // Add the cantor script directory to search path
     args << QLatin1String("--eval");
     args << QString::fromLatin1("addpath %1;").arg(octaveScriptInstallDir);
 
     // Print the temp dir, used for plot files
     args << QLatin1String("--eval");
     args << QLatin1String("printf('%s\\n', ['____TMP_DIR____ = ' tempdir]);");
 
     // Do not show extra text in help commands
     args << QLatin1String("--eval");
     args << QLatin1String("suppress_verbose_help_message(1);");
 
     if (OctaveSettings::integratePlots())
     {
         // Do not show the popup when plotting, rather only print to a file
         args << QLatin1String("--eval");
         args << QLatin1String("set (0, \"defaultfigurevisible\",\"off\");");
         args << QLatin1String("--eval");
         args << QLatin1String("graphics_toolkit gnuplot;");
     }
     else
     {
         args << QLatin1String("--eval");
         args << QLatin1String("set (0, \"defaultfigurevisible\",\"on\");");
     }
 
     if (OctaveSettings::integratePlots())
     {
         m_watch = new KDirWatch(this);
         m_watch->setObjectName(QLatin1String("OctaveDirWatch"));
         connect (m_watch, SIGNAL(dirty(QString)), SLOT(plotFileChanged(QString)) );
     }
 
     m_process->setProgram ( OctaveSettings::path().toLocalFile(), args );
     qDebug() << "starting " << m_process->program();
     m_process->setOutputChannelMode ( KProcess::SeparateChannels );
     m_process->start();
     m_process->waitForStarted();
 
     // Got tmp dir
     bool loginFinished = false;
     QString input;
     while (!loginFinished)
     {
         m_process->waitForReadyRead();
         input += QString::fromLatin1(m_process->readAllStandardOutput());
         qDebug() << "login input: " << input;
         if (input.contains(QLatin1String("____TMP_DIR____")))
             {
                 m_tempDir = input;
                 m_tempDir.remove(0,18);
                 m_tempDir.chop(1); // isolate the tempDir's location
                 qDebug() << "Got temporary file dir:" << m_tempDir;
                 if (m_watch)
                 {
                     m_watch->addDir(m_tempDir, KDirWatch::WatchFiles);
                 }
                 loginFinished = true;
             }
     }
 
     connect ( m_process, SIGNAL (readyReadStandardOutput()), SLOT (readOutput()) );
     connect ( m_process, SIGNAL (readyReadStandardError()), SLOT (readError()) );
     connect ( m_process, SIGNAL (error(QProcess::ProcessError)), SLOT (processError()) );
 
     if(!OctaveSettings::self()->autorunScripts().isEmpty()){
         QString autorunScripts = OctaveSettings::self()->autorunScripts().join(QLatin1String("\n"));
 
         evaluateExpression(autorunScripts, OctaveExpression::DeleteOnFinish, true);
         forceVariableUpdate();
     }
 
     changeStatus(Cantor::Session::Done);
     emit loginDone();
     qDebug()<<"login done";
 }
 
 void OctaveSession::logout()
 {
     qDebug()<<"logout";
 
     if(!m_process)
         return;
 
     disconnect(m_process, nullptr, this, nullptr);
 
     // if(status()==Cantor::Session::Running)
     // TODO: terminate the running expressions first
 
     m_process->write("exit\n");
     qDebug()<<"waiting for octave to finish";
     m_process->waitForFinished();
     qDebug()<<"octave exit finished";
 
     if(m_process->state() != QProcess::NotRunning)
     {
         m_process->kill();
         qDebug()<<"octave still running, process kill enforced";
     }
 
     expressionQueue().clear();
     delete m_process;
     m_process = nullptr;
 
 
     m_tempDir.clear();
     m_output.clear();
     m_previousPromptNumber = 1;
 
-    static_cast<OctaveVariableModel*>(variableModel())->clearVariables();
+    OctaveVariableModel* model = static_cast<OctaveVariableModel*>(variableModel());
+    model->clearVariables();
 
     changeStatus(Status::Disable);
 
     qDebug()<<"logout done";
 }
 
 void OctaveSession::interrupt()
 {
     if(!expressionQueue().isEmpty())
     {
         qDebug()<<"interrupting " << expressionQueue().first()->command();
         if(m_process->state() != QProcess::NotRunning)
         {
 #ifndef Q_OS_WIN
             const int pid=m_process->pid();
             kill(pid, SIGINT);
 #else
             ; //TODO: interrupt the process on windows
 #endif
         }
         foreach (Cantor::Expression* expression, expressionQueue())
             expression->setStatus(Cantor::Expression::Interrupted);
         expressionQueue().clear();
 
         // Cleanup inner state and call octave prompt printing
         // If we move this code for interruption to Session, we need add function for
         // cleaning before setting Done status
         m_output.clear();
         m_process->write("\n");
 
         qDebug()<<"done interrupting";
     }
 
     changeStatus(Cantor::Session::Done);
 }
 
 void OctaveSession::processError()
 {
     qDebug() << "processError";
     emit error(m_process->errorString());
 }
 
 Cantor::Expression* OctaveSession::evaluateExpression ( const QString& command, Cantor::Expression::FinishingBehavior finishingBehavior, bool internal )
 {
     qDebug() << "evaluating: " << command;
     OctaveExpression* expression = new OctaveExpression ( this, internal);
     expression->setCommand ( command );
     expression->setFinishingBehavior ( finishingBehavior );
     expression->evaluate();
 
     return expression;
 }
 
 void OctaveSession::runFirstExpression()
 {
     OctaveExpression* expression = static_cast<OctaveExpression*>(expressionQueue().first());
     connect(expression, SIGNAL(statusChanged(Cantor::Expression::Status)), this, SLOT(currentExpressionStatusChanged(Cantor::Expression::Status)));
     QString command = expression->internalCommand();
     expression->setStatus(Cantor::Expression::Computing);
     if (isDoNothingCommand(command))
         expression->setStatus(Cantor::Expression::Done);
     else
     {
         m_process->write ( command.toLocal8Bit() );
     }
 }
 
 void OctaveSession::readError()
 {
     qDebug() << "readError";
     QString error = QString::fromLocal8Bit(m_process->readAllStandardError());
     if (!expressionQueue().isEmpty() && !error.isEmpty())
     {
         OctaveExpression* const exp = static_cast<OctaveExpression*>(expressionQueue().first());
         if (m_syntaxError)
         {
             m_syntaxError = false;
             exp->parseError(i18n("Syntax Error"));
         }
         else
             exp->parseError(error);
 
         m_output.clear();
     }
 }
 
 void OctaveSession::readOutput()
 {
     qDebug() << "readOutput";
     while (m_process->bytesAvailable() > 0)
     {
         QString line = QString::fromLocal8Bit(m_process->readLine());
         qDebug()<<"start parsing " << "  " << line;
         if (line.contains(m_prompt))
         {
             const int promptNumber = m_prompt.cap(1).toInt();
             if (!expressionQueue().isEmpty())
             {
                 const QString& command = expressionQueue().first()->command();
                 if (m_previousPromptNumber + 1 == promptNumber || isSpecialOctaveCommand(command))
                 {
                     if (!expressionQueue().isEmpty())
                         static_cast<OctaveExpression*>(expressionQueue().first())->parseOutput(m_output);
                 }
                 else
                 {
                     // Error command don't increase octave prompt number (usually, but not always)
                     readError();
                 }
             }
             m_previousPromptNumber = promptNumber;
             m_output.clear();
         }
         else if (line.contains(m_subprompt) && m_subprompt.cap(1).toInt() == m_previousPromptNumber)
         {
             // User don't write finished octave statement (for example, write 'a = [1,2, ' only), so
             // octave print subprompt and waits input finish.
             m_syntaxError = true;
             qDebug() << "subprompt catch";
             m_process->write(")]'\"\n"); // forse exit from subprompt
             m_output.clear();
         }
         else
             m_output += line;
     }
 }
 
 void OctaveSession::currentExpressionStatusChanged(Cantor::Expression::Status status)
 {
     qDebug() << "currentExpressionStatusChanged";
     switch (status)
     {
     case Cantor::Expression::Done:
     case Cantor::Expression::Error:
         finishFirstExpression();
         break;
 
     default:
         break;
     }
 }
 
 void OctaveSession::plotFileChanged(const QString& filename)
 {
     if (!QFile::exists(filename) || !filename.split(QLatin1Char('/')).last().contains(QLatin1String("c-ob-")))
     {
         return;
     }
 
     if (!expressionQueue().isEmpty())
     {
         static_cast<OctaveExpression*>(expressionQueue().first())->parsePlotFile(filename);
     }
 }
 
 Cantor::CompletionObject* OctaveSession::completionFor ( const QString& cmd, int index )
 {
     return new OctaveCompletionObject ( cmd, index, this );
 }
 
 Cantor::SyntaxHelpObject* OctaveSession::syntaxHelpFor ( const QString& cmd )
 {
     return new OctaveSyntaxHelpObject ( cmd, this );
 }
 
 QSyntaxHighlighter* OctaveSession::syntaxHighlighter ( QObject* parent )
 {
     OctaveHighlighter* highlighter = new OctaveHighlighter ( parent, this );
 
     OctaveVariableModel* model = static_cast<OctaveVariableModel*>(variableModel());
     connect (model, &Cantor::DefaultVariableModel::variablesAdded, highlighter, &OctaveHighlighter::addUserVariable);
     connect (model, &Cantor::DefaultVariableModel::variablesRemoved, highlighter, &OctaveHighlighter::removeUserVariable);
 
     return highlighter;
 }
 
 void OctaveSession::runSpecificCommands()
 {
     m_process->write("figure(1,'visible','off')");
 }
 
 bool OctaveSession::isDoNothingCommand(const QString& command)
 {
     return PROMPT_UNCHANGEABLE_COMMAND.exactMatch(command) || command.isEmpty();
 }
 
 bool OctaveSession::isSpecialOctaveCommand(const QString& command)
 {
     return command.contains(QLatin1String("completion_matches"));
 }
diff --git a/src/lib/session.cpp b/src/lib/session.cpp
index 2121dbf0..32a82a36 100644
--- a/src/lib/session.cpp
+++ b/src/lib/session.cpp
@@ -1,181 +1,188 @@
 /*
     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 "session.h"
 using namespace Cantor;
 
 #include "backend.h"
 #include "defaultvariablemodel.h"
 
 #include <QTimer>
 #include <QQueue>
 
 class Cantor::SessionPrivate
 {
   public:
     SessionPrivate() : backend(nullptr), status(Session::Disable), typesettingEnabled(false), expressionCount(0), variableModel(nullptr), needUpdate(false)
     {
     }
 
     Backend* backend;
     Session::Status status;
     bool typesettingEnabled;
     int expressionCount;
     QList<Cantor::Expression*> expressionQueue;
     DefaultVariableModel* variableModel;
     bool needUpdate;
 };
 
 Session::Session( Backend* backend ) : QObject(backend), d(new SessionPrivate)
 {
     d->backend=backend;
 }
 
 Session::Session( Backend* backend, DefaultVariableModel* model) : QObject(backend), d(new SessionPrivate)
 {
     d->backend=backend;
     d->variableModel=model;
 }
 
 Session::~Session()
 {
     delete d;
 }
 
 QList<Expression*>& Cantor::Session::expressionQueue() const
 {
     return d->expressionQueue;
 }
 
 void Session::enqueueExpression(Expression* expr)
 {
     d->expressionQueue.append(expr);
 
     //run the newly added expression immediately if it's the only one in the queue
     if (d->expressionQueue.size() == 1)
     {
         changeStatus(Cantor::Session::Running);
         runFirstExpression();
     }
     else
         expr->setStatus(Cantor::Expression::Queued);
 }
 
 void Session::runFirstExpression()
 {
 
 }
 
 void Session::finishFirstExpression()
 {
-    d->needUpdate |= !d->expressionQueue.takeFirst()->isInternal();
+    if (!d->expressionQueue.isEmpty())
+        d->needUpdate |= !d->expressionQueue.takeFirst()->isInternal();
+
     if (d->expressionQueue.isEmpty())
         if (d->variableModel && d->needUpdate)
         {
             d->variableModel->update();
             d->needUpdate = false;
         }
         else
             changeStatus(Done);
     else
         runFirstExpression();
 }
 
 Backend* Session::backend()
 {
     return d->backend;
 }
 
 Cantor::Session::Status Session::status()
 {
     return d->status;
 }
 
 void Session::changeStatus(Session::Status newStatus)
 {
     d->status=newStatus;
     emit statusChanged(newStatus);
 }
 
 void Session::setTypesettingEnabled(bool enable)
 {
     d->typesettingEnabled=enable;
 }
 
 bool Session::isTypesettingEnabled()
 {
     return d->typesettingEnabled;
 }
 
 void Session::setWorksheetPath(const QString& path)
 {
     Q_UNUSED(path);
     return;
 }
 
 CompletionObject* Session::completionFor(const QString& cmd, int index)
 {
     Q_UNUSED(cmd);
     Q_UNUSED(index);
     //Return 0 per default, so Backends not offering tab completions don't have
     //to reimplement this. This method should only be called on backends with
     //the Completion Capability flag
 
     return nullptr;
 }
 
 SyntaxHelpObject* Session::syntaxHelpFor(const QString& cmd)
 {
     Q_UNUSED(cmd);
 
     //Return 0 per default, so Backends not offering tab completions don't have
     //to reimplement this. This method should only be called on backends with
     //the SyntaxHelp Capability flag
     return nullptr;
 }
 
 QSyntaxHighlighter* Session::syntaxHighlighter(QObject* parent)
 {
     Q_UNUSED(parent);
     return nullptr;
 }
 
 QAbstractItemModel* Session::variableModel()
 {
     //Return deafult session model per default
     //By default, variableModel is nullptr, so Backends not offering variable management don't
     //have to reimplement this. This method should only be called on backends with
     //VariableManagement Capability flag
     return d->variableModel;
 }
 
 void Session::forceVariableUpdate()
 {
     if (d->variableModel)
     {
         d->variableModel->update();
         d->needUpdate = false;
     }
 }
 
+void Cantor::Session::setVariableModel(Cantor::DefaultVariableModel* model)
+{
+    d->variableModel = model;
+}
+
 int Session::nextExpressionId()
 {
     return d->expressionCount++;
 }
diff --git a/src/lib/session.h b/src/lib/session.h
index 7b2c516d..7b27c1f2 100644
--- a/src/lib/session.h
+++ b/src/lib/session.h
@@ -1,242 +1,247 @@
 /*
     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>
  */
 
 #ifndef _SESSION_H
 #define _SESSION_H
 
 #include <QObject>
 
 #include "cantor_export.h"
 
 #include "expression.h"
 
 class QTextEdit;
 class QSyntaxHighlighter;
 class QAbstractItemModel;
 
 /**
  * Namespace collecting all Classes of the Cantor Libraries
  */
 namespace Cantor
 {
 class Backend;
 class SessionPrivate;
 class CompletionObject;
 class SyntaxHelpObject;
 class DefaultVariableModel;
 
 /**
  * The Session object is the main class used to interact with a Backend.
  * It is used to evaluate Expressions, get completions, syntax highlighting, etc.
  *
  * @author Alexander Rieder
  */
 class CANTOR_EXPORT Session : public QObject
 {
   Q_OBJECT
   public:
     enum Status {
       Running, ///< the session is busy, running some expression
       Done,    ///< the session has done all the jobs, and is now waiting for more
       Disable  ///< the session don't login yet, or already logout
     };
 
     /**
      * Create a new Session. This should not yet set up the complete session,
      * thats job of the login() function
      * @see login()
      */
     explicit Session( Backend* backend);
 
     /**
      * Similar to Session::Session, but also specify variable model for automatically handles model's updates
      */
     explicit Session( Backend* backend, DefaultVariableModel* model);
 
     /**
      * Destructor
      */
     ~Session() override;
 
     /**
      * Login to the Session. In this function you should do anything needed to set up
      * the session, and make it ready for usage. The method should be implemented non-blocking.
      * Emit loginStarted() prior to connection to the actual backend in order to notify cantor_part about it.
      * If the logging in is completed, the loginDone() signal must be emitted
      */
     virtual void login() = 0;
     /**
      * Log out of the Session. Destroy everything specific to a single session, e.g.
      * stop all the running processes etc. Also logout session status must be Status::Disable
      * NOTE: restarting the session consists of first logout() and then login()
      */
     virtual void logout() = 0;
 
     /**
      * Passes the given command to the backend and returns a Pointer
      * to a new Expression object, which will emit the gotResult()
      * signal as soon as the computation is done. The result will
      * then be accessible by Expression::result()
      * @param command the command that should be run by the backend.
      * @param finishingBehavior the FinishingBehaviour that should be used for this command. @see Expression::FinishingBehaviour
      * @param internal true, if it is an internal command @see Expression::Expression(Session*, bool)
      * @return an Expression object, representing this command
      */
     virtual Expression* evaluateExpression(const QString& command, Expression::FinishingBehavior finishingBehavior = Expression::FinishingBehavior::DoNotDelete, bool internal = false) = 0;
 
     /**
      * Append the expression to queue .
      * @see expressionQueue() const
      */
     void enqueueExpression(Expression*);
 
     /**
      * Interrupts all the running calculations in this session
      */
     virtual void interrupt() = 0;
 
     /**
      * Returns tab-completion, for this command/command-part.
      * The return type is a CompletionObject. The fetching
      * of the completions works asynchronously, you'll have to
      * listen to the done() Signal of the returned object
      * @param cmd The partial command that should be completed
      * @param index The index (cursor position) at which completion
      * was invoked. Defaults to -1, indicating the end of the string.
      * @return a Completion object, representing this completion
      * @see CompletionObject
      */
     virtual CompletionObject* completionFor(const QString& cmd, int index = -1);
 
     /**
      * Returns Syntax help, for this command.
      * It returns a SyntaxHelpObject, that will fetch the
      * needed information asynchronously. You need to listen
      * to the done() Signal of the Object
      * @param cmd the command, syntax help is requested for
      * @return SyntaxHelpObject, representing the help request
      * @see SyntaxHelpObject
      */
     virtual SyntaxHelpObject* syntaxHelpFor(const QString& cmd);
 
     /**
      * returns a syntax highlighter for this session
      * @param parent QObject the Highlighter's parent
      * @return QSyntaxHighlighter doing the highlighting for this Session
      */
     virtual QSyntaxHighlighter* syntaxHighlighter(QObject* parent);
 
     /**
      * returns a Model to interact with the variables
      * @return QAbstractItemModel to interact with the variables
      */
     virtual QAbstractItemModel* variableModel();
 
     /**
      * Enables/disables Typesetting for this session.
      * For this setting to make effect, the Backend must support
      * LaTeX typesetting (as indicated by the capabilities() flag.
      * @param enable true to enable, false to disable typesetting
      */
     virtual void setTypesettingEnabled(bool enable);
 
     /**
     * Updates the worksheet path in the session.
     * This can be useful to set the path of the currently opened
     * Cantor project file in the backend interpreter.
     * Default implementation does nothing. Derived classes have
     * to implement the proper logic if this feature is supported.
     * @param path the new absolute path to the worksheet.
     */
     virtual void setWorksheetPath(const QString& path);
 
     /**
      * Returns the Backend, this Session is for
      * @return the Backend, this Session is for
      */
     Backend* backend();
 
     /**
      * Returns the status this Session has
      * @return the status this Session has
      */
     Cantor::Session::Status status();
     /**
      * Returns whether typesetting is enabled or not
      * @return whether typesetting is enabled or not
      */
     bool isTypesettingEnabled();
 
     /**
      * Returns the next available Expression id
      * It is basically a counter, incremented for
      * each new Expression
      * @return next Expression id
      */
     int nextExpressionId();
 
   protected:
     /**
      * Change the status of the Session. This will cause the
      * stausChanged signal to be emitted
      * @param newStatus the new status of the session
      */
     void changeStatus(Cantor::Session::Status newStatus);
 
     /**
      * Session can process one single expression at one time.
      * Any other expressions submitted by the user are queued first until they get processed.
      * The expression queue implements the FIFO mechanism.
      * The queud expression have the status \c Expression::Queued.
      */
     QList<Expression*>& expressionQueue() const;
 
     /**
      * Execute first expression in expression queue.
      * Also, this function changes the status from Queued to Computing.
      * @see expressionQueue() const
      */
     virtual void runFirstExpression();
 
     /**
      * Opposite action to Session::runFirstExpression()
      * This method dequeue the expression and go to next expression, if queue not empty
      * Also, this method updates variableModel, if needed
      * If queue empty, session change status to Done
      */
     virtual void finishFirstExpression();
 
     /**
      * Starts variable update immideatly, usefull for subclasses, which run internal command
      * which could change variables listen
      */
     virtual void forceVariableUpdate();
 
+    /**
+     * Setting variable model, usefull, if model constructor requires functional session
+     */
+    void setVariableModel(DefaultVariableModel* model);
+
 Q_SIGNALS:
     void statusChanged(Cantor::Session::Status newStatus);
     void loginStarted();
     void loginDone();
     void error(const QString& msg);
 
   private:
     SessionPrivate* d;
 };
 }
 #endif /* _SESSION_H */