diff --git a/src/backends/maxima/maximaexpression.cpp b/src/backends/maxima/maximaexpression.cpp
index 33d37847..9ec21eb1 100644
--- a/src/backends/maxima/maximaexpression.cpp
+++ b/src/backends/maxima/maximaexpression.cpp
@@ -1,810 +1,819 @@
 /*
     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>
  */
 
 #include "maximaexpression.h"
 
 #include <config-cantorlib.h>
 
 #include "maximasession.h"
 #include "textresult.h"
 #include "epsresult.h"
 #include "imageresult.h"
 #include "helpresult.h"
 #include "latexresult.h"
 #include "settings.h"
 
 #include <QDir>
 #include <QTemporaryFile>
 
 #include <KLocalizedString>
 #include <QDebug>
 #include <QTimer>
 #include <QRegExp>
 #include <QChar>
 #include <QUrl>
 
 MaximaExpression::MaximaExpression( Cantor::Session* session, bool internal ) : Cantor::Expression(session, internal),
     m_tempFile(nullptr),
     m_isHelpRequest(false),
     m_isPlot(false),
     m_plotResult(nullptr),
     m_plotResultIndex(-1),
     m_gotErrorContent(false)
 {
 }
 
+MaximaExpression::~MaximaExpression() {
+    if(m_tempFile)
+        delete m_tempFile;
+}
+
 void MaximaExpression::evaluate()
 {
     //until we get the real output Id from maxima, set it to invalid
     setId(-1);
 
     m_isHelpRequest=false;
-    m_isPlot=false;
     m_gotErrorContent=false;
+
     if(m_tempFile)
-        m_tempFile->deleteLater();
-    m_tempFile=nullptr;
-    m_plotResult = nullptr;
-    m_plotResultIndex = -1;
+    {
+        delete m_tempFile;
+        m_tempFile = nullptr;
+        m_isPlot = false;
+        m_plotResult = nullptr;
+        m_plotResultIndex = -1;
+    }
+
     //check if this is a ?command
     if(command().startsWith(QLatin1String("??"))
         || command().startsWith(QLatin1String("describe("))
         || command().startsWith(QLatin1String("example("))
         || command().startsWith(QLatin1String(":lisp(cl-info::info-exact")))
         m_isHelpRequest=true;
 
     if(command().contains(QRegExp(QLatin1String("(?:plot2d|plot3d|contour_plot)\\s*\\([^\\)]"))) && MaximaSettings::self()->integratePlots() && !command().contains(QLatin1String("ps_file")))
     {
         m_isPlot=true;
 #ifdef WITH_EPS
         m_tempFile=new QTemporaryFile(QDir::tempPath() + QLatin1String("/cantor_maxima-XXXXXX.eps" ));
 #else
         m_tempFile=new QTemporaryFile(QDir::tempPath() + QLatin1String("/cantor_maxima-XXXXXX.png"));
 #endif
         m_tempFile->open();
 
         m_fileWatch.removePaths(m_fileWatch.files());
         m_fileWatch.addPath(m_tempFile->fileName());
         connect(&m_fileWatch, &QFileSystemWatcher::fileChanged, this, &MaximaExpression::imageChanged,  Qt::UniqueConnection);
     }
 
     const QString& cmd=command();
 
     bool isComment = true;
     int commentLevel = 0;
     bool inString = false;
     for (int i = 0; i < cmd.size(); ++i) {
         if (cmd[i] == QLatin1Char('\\')) {
             ++i; // skip the next character
             if (commentLevel == 0 && !inString) {
                 isComment = false;
             }
         } else if (cmd[i] == QLatin1Char('"') && commentLevel == 0) {
             inString = !inString;
             isComment = false;
         } else if (cmd.mid(i,2) == QLatin1String("/*") && !inString) {
             ++commentLevel;
             ++i;
         } else if (cmd.mid(i,2) == QLatin1String("*/") && !inString) {
             if (commentLevel == 0) {
                 qDebug() << "Comments mismatched!";
                 setErrorMessage(i18n("Error: Too many */"));
                 setStatus(Cantor::Expression::Error);
                 return;
             }
             ++i;
             --commentLevel;
         } else if (isComment && commentLevel == 0 && !cmd[i].isSpace()) {
             isComment = false;
         }
     }
 
     if (commentLevel > 0) {
         qDebug() << "Comments mismatched!";
         setErrorMessage(i18n("Error: Too many /*"));
         setStatus(Cantor::Expression::Error);
         return;
     }
     if (inString) {
         qDebug() << "String not closed";
         setErrorMessage(i18n("Error: expected \" before ;"));
         setStatus(Cantor::Expression::Error);
         return;
     }
     if(isComment)
     {
         setStatus(Cantor::Expression::Done);
         return;
     }
 
     session()->enqueueExpression(this);
 }
 
 void MaximaExpression::interrupt()
 {
     qDebug()<<"interrupting";
     setStatus(Cantor::Expression::Interrupted);
 }
 
 QString MaximaExpression::internalCommand()
 {
     QString cmd=command();
 
     if(m_isPlot)
     {
         if(!m_tempFile)
         {
             qDebug()<<"plotting without tempFile";
             return QString();
         }
         QString fileName = m_tempFile->fileName();
 
 #ifdef WITH_EPS
         const QString psParam=QLatin1String("[gnuplot_ps_term_command, \"set size 1.0,  1.0; set term postscript eps color solid \"]");
         const QString plotParameters = QLatin1String("[ps_file, \"")+ fileName+QLatin1String("\"],")+psParam;
 #else
         const QString plotParameters = QLatin1String("[gnuplot_term, \"png size 500,340\"], [gnuplot_out_file, \"")+fileName+QLatin1String("\"]");
 
 #endif
         cmd.replace(QRegExp(QLatin1String("((plot2d|plot3d|contour_plot)\\s*\\(.*)\\)([;\n]|$)")), QLatin1String("\\1, ")+plotParameters+QLatin1String(");"));
 
     }
 
     if (!cmd.endsWith(QLatin1Char('$')))
     {
         if (!cmd.endsWith(QLatin1String(";")))
             cmd+=QLatin1Char(';');
     }
 
     //replace all newlines with spaces, as maxima isn't sensitive about
     //whitespaces, and without newlines the whole command
     //is executed at once, without outputting an input
     //prompt after each line
     cmd.replace(QLatin1Char('\n'), QLatin1Char(' '));
 
     //lisp-quiet doesn't print a prompt after the command
     //is completed, which causes the parsing to hang.
     //replace the command with the non-quiet version
     cmd.replace(QRegExp(QLatin1String("^:lisp-quiet")), QLatin1String(":lisp"));
 
     return cmd;
 }
 
 void MaximaExpression::forceDone()
 {
     qDebug()<<"forcing Expression state to DONE";
     setResult(nullptr);
     setStatus(Cantor::Expression::Done);
 }
 
 void MaximaExpression::addInformation(const QString& information)
 {
     qDebug()<<"adding information";
     QString inf=information;
     if(!inf.endsWith(QLatin1Char(';')))
         inf+=QLatin1Char(';');
     Cantor::Expression::addInformation(inf);
 
     dynamic_cast<MaximaSession*>(session())->sendInputToProcess(inf+QLatin1Char('\n'));
 }
 
 
 //The maxima backend is modified, so that it outputs
 //xml-style tags around outputs, input prompts etc.
 //the following are some simple helper functions to facilitate parsing
 inline void skipWhitespaces(int* idx, const QString& txt)
 {
     for(;*idx < txt.size() && (txt[*idx]).isSpace();++(*idx));
 }
 
 QStringRef readXmlOpeningTag(int* idx, const QString& txt, bool* isComplete=nullptr)
 {
     qDebug()<<"trying to read an opening tag";
 
     if (*idx >= txt.size())
         return QStringRef();
 
     skipWhitespaces(idx, txt);
 
     if(isComplete)
         *isComplete=false;
 
     if(txt[*idx]!=QLatin1Char('<'))
     {
         qDebug()<<"This is NOT AN OPENING TAG."<<endl
                 <<"Dropping everything until next opening; This starts with a " <<txt[*idx];
         int newIdx=txt.indexOf(QLatin1Char('<'), *idx);
         if(newIdx==-1) //no more opening brackets in this string
         {
             return QStringRef();
         }else
         {
             (*idx)=newIdx+1;
         }
 
     }else
     {
         ++ (*idx);
     }
 
     int startIndex=*idx;
     int length=0;
     while(*idx<txt.size())
     {
         const QChar c=txt[*idx];
         ++(*idx);
 
         if(c==QLatin1Char('>'))
         {
             if(isComplete)
                 *isComplete=true;
             break;
         }else
             length++;
     }
 
     return QStringRef(&txt, startIndex, length);
 }
 
 QStringRef readXmlTagContent(int* idx, const QString& txt, const QStringRef& name, bool* isComplete=nullptr)
 {
     bool readingClosingTag=false;
     int contentStartIdx=*idx;
     int contentLength=0;
     int currentTagStartIdx=-1;
     int currentTagLength=0;
 
     if(isComplete)
         *isComplete=false;
 
     while(*idx<txt.size())
     {
         const QChar c=txt[*idx];
 
         if(c==QLatin1Char('/')&&(*idx)>0&&txt[(*idx)-1]==QLatin1Char('<'))
         {
             //remove the opening <
             contentLength--;
             currentTagStartIdx=*idx+1;
             currentTagLength=0;
             readingClosingTag=true;
         }
         else if(readingClosingTag)
         {
             if(c==QLatin1Char('>'))
             {
                 const QStringRef currentTagName(&txt, currentTagStartIdx, currentTagLength);
 
                 if(currentTagName==name)
                 {
                     //eat up the closing >
                     ++(*idx);
                     if(isComplete)
                         (*isComplete)=true;
                     break;
                 }
 
                 readingClosingTag=false;
             }else
                 currentTagLength++;
         }
         else
             contentLength++;
 
 
         ++(*idx);
 
     }
 
     if(contentStartIdx+contentLength>txt.size())
     {
         qDebug()<<"something is wrong with the content-length "<<contentStartIdx+contentLength<<
             " vs: "<<txt.size();
     }
     return QStringRef(&txt,contentStartIdx, contentLength);
 }
 
 bool MaximaExpression::parseOutputOld(QString& out)
 {
     enum ParserStatus{ReadingOpeningTag, ReadingClosingTag, ReadingText};
     int idx=0;
     int numResults=0;
     QString textBuffer;
     QString latexBuffer;
     QString errorBuffer;
 
     Cantor::Result* result=nullptr;
     while(idx<out.size())
     {
         skipWhitespaces(&idx, out);
 
         //first read the part not enclosed in tags. it most likely belongs to an error message
         int idx1=out.indexOf(QLatin1String("<cantor-prompt>"), idx);
         int idx2=out.indexOf(QLatin1String("<cantor-result>"), idx);
 
         idx1=(idx1==-1) ? out.size():idx1;
         idx2=(idx2==-1) ? out.size():idx2;
         int newIdx=qMin(idx1, idx2);
 
         if(newIdx>idx)
         {
             const QString& err=out.mid(idx, newIdx-idx);
             if(!err.isEmpty())
                 m_gotErrorContent=true;
             errorBuffer+=err;
             qDebug()<<"the unmatched part of the output is: "<<err;
             idx=newIdx;
         }
 
         const QStringRef& tag=readXmlOpeningTag(&idx, out);
 
         if(tag==QLatin1String("cantor-result"))
         {
             qDebug()<<"got a result";
 
             if(numResults>0)
             {
                 textBuffer.append(QLatin1String("\n"));
                 latexBuffer.append(QLatin1String("\n"));
             }
 
             result=parseResult(&idx, out, textBuffer, latexBuffer);
             numResults++;
 
             qDebug()<<"got "<<numResults<<"th result.";
 
         }else if (tag==QLatin1String("cantor-prompt"))
         {
             qDebug()<<"i got a prompt: "<<idx;
 
             skipWhitespaces(&idx, out);
 
             //We got a child tag
             if(out[idx]==QLatin1Char('<'))
             {
                 const QStringRef& childTag=readXmlOpeningTag(&idx, out);
                 qDebug()<<"got an information request!"<<childTag;
 
                 QStringRef text;
                 QStringRef latex;
                 while(idx<out.size())
                 {
                     const QStringRef& type=readXmlOpeningTag(&idx, out);
                     qDebug()<<"its a "<<type;
                     if(type==QLatin1String("/cantor-result"))
                         break;
                     const QStringRef& content=readXmlTagContent(&idx, out, type);
 
                     if(type==QLatin1String("cantor-text"))
                         text=content;
                     else if(type==QLatin1String("cantor-latex"))
                         latex=content;
 
                     qDebug()<<"content: "<<content;
                 }
 
                 bool isComplete;
                 //readup the rest of the element and discard it
                 readXmlTagContent(&idx, out,tag, &isComplete);
 
                 if(!isComplete)
                     return false;
 
                 //send out the information request
                 emit needsAdditionalInformation(text.toString());
 
                 out=out.mid(idx);
                 idx=0;
 
                 return true;
 
             }else //got a regular prompt. Just read it all
             {
                 bool isComplete;
                 readXmlTagContent(&idx, out, tag, &isComplete);
 
                 if(!isComplete)
                     return false;
 
                 m_errorBuffer+=errorBuffer;
                 if(!m_errorBuffer.trimmed().isEmpty())
                 {
                     if(command().startsWith(QLatin1String(":lisp"))||command().startsWith(QLatin1String(":lisp-quiet")))
                     {
                         if(result)
                         {
                             if(result->type()==Cantor::TextResult::Type)
                                 m_errorBuffer.prepend(dynamic_cast<Cantor::TextResult*>(result)->plain()+QLatin1String("\n"));
                             else if(result->type()==Cantor::LatexResult::Type)
                                 m_errorBuffer.prepend(dynamic_cast<Cantor::LatexResult*>(result)->plain()+QLatin1String("\n"));
                         }
 
                         Cantor::TextResult* result=new Cantor::TextResult(m_errorBuffer);
                         setResult(result);
                         setStatus(Cantor::Expression::Done);
                     }else
                     if(m_isHelpRequest) //Help Messages are also provided in the errorBuffer.
                     {
                         Cantor::HelpResult* result=new Cantor::HelpResult(m_errorBuffer);
                         setResult(result);
 
                         setStatus(Cantor::Expression::Done);
                     }else
                     {
                         if(result)
                         {
                             qDebug()<<"result: "<<result->toHtml();
                             if(result->type()==Cantor::TextResult::Type)
                                 m_errorBuffer.prepend(dynamic_cast<Cantor::TextResult*>(result)->plain()+QLatin1String("\n"));
                             else if(result->type()==Cantor::LatexResult::Type)
                                 m_errorBuffer.prepend(dynamic_cast<Cantor::LatexResult*>(result)->plain()+QLatin1String("\n"));
                         }
 
                         qDebug()<<"errorBuffer: "<<m_errorBuffer;
 
 
                         setErrorMessage(m_errorBuffer.trimmed());
                         if(m_gotErrorContent)
                             setStatus(Cantor::Expression::Error);
                         else
                             setStatus(Cantor::Expression::Done);
                     }
                 }
                 else
                 {
                     //if we got an error message, but also a result, lets just+
                     //assume that it was just a warning, as obviously something worked
                     if(errorMessage().isEmpty()||result!=nullptr)
                     {
                         setResult(result);
                         setStatus(Cantor::Expression::Done);
                     }
                     else
                     {
                         if(!result)
                             setStatus(Cantor::Expression::Error);
 
                     }
                 }
 
                 out=out.mid(idx);
                 idx=0;
 
                 return true;
             }
         }else
         {
             qDebug()<<"unknown tag"<<tag;
         }
     }
 
     //show partial result
     setResult(result);
     return false;
 }
 
 Cantor::Result* MaximaExpression::parseResult(int* idx, QString& out,
                                               QString& textBuffer, QString& latexBuffer)
 {
     bool isLatexComplete=false;
     QString latex;
     QString text;
 
     while(*idx<out.size())
     {
         bool isComplete;
         const QStringRef& type=readXmlOpeningTag(idx, out);
 
         if(type==QLatin1String("/cantor-result"))
             break;
 
         const QStringRef& content=readXmlTagContent(idx, out, type, &isComplete);
 
         if(type==QLatin1String("cantor-text"))
             text=content.toString().trimmed();
         else if(type==QLatin1String("cantor-latex"))
         {
             isLatexComplete=isComplete;
             latex=content.toString().trimmed();
         }
     }
 
     QRegExp outputPromptRegexp=QRegExp(QLatin1Char('^')+MaximaSession::MaximaOutputPrompt.pattern());
     int idxOfPrompt=outputPromptRegexp.indexIn(text);
     text.remove(idxOfPrompt, outputPromptRegexp.matchedLength());
 
     //find the number if this output in the MaximaOutputPrompt
     QString prompt=outputPromptRegexp.cap(0).trimmed();
     bool ok;
     QString idString=prompt.mid(3, prompt.length()-4);
     int id=idString.toInt(&ok);
     if(ok)
         setId(id);
     else
         setId(-1);
     qDebug()<<"prompt: "<<prompt<<" id: "<<id;
 
     if(m_tempFile)
     {
         QTimer::singleShot(500, this, SLOT(imageChanged()));
     }
 
     Cantor::TextResult* result=nullptr;
 
     //if this is not the first result, prepend the results
     //found in the earlier tags.
     textBuffer.append(text);
 
     //if the <latex> element wasn't read completely, there
     //is no point in trying to render it. Use text for
     //incomplete results.
     if(!isLatexComplete
        ||(latexBuffer.trimmed().isEmpty()&&latex.isEmpty())
        ||m_isHelpRequest||isInternal())
     {
         qDebug()<<"using text";
         result=new Cantor::TextResult(textBuffer);
     }else
     {
         qDebug()<<"using latex";
         //strip away the latex code for the label.
         //it is contained in an \mbox{} call
         int i;
         int pcount=0;
         for(i=latex.indexOf(QLatin1String("\\mbox{"))+5;i<latex.size();i++)
         {
             if(latex[i]==QLatin1Char('{'))
                 pcount++;
             else if(latex[i]==QLatin1Char('}'))
                 pcount--;
 
             if(pcount==0)
                 break;
         }
 
         latex=latex.mid(i+1);
 
         //no need to render empty latex.
         if(latexBuffer.trimmed().isEmpty()&&latex.trimmed().isEmpty())
         {
             if(m_isPlot)
                 result=new Cantor::TextResult(i18n("Waiting for Image..."));
             else
                 result=nullptr;
         }else
         {
             latex.prepend(QLatin1String("\\begin{eqnarray*}\n"));
             latex.append(QLatin1String("\n\\end{eqnarray*}"));
             latexBuffer.append(latex);
             result=new Cantor::TextResult(latexBuffer, textBuffer);
             result->setFormat(Cantor::TextResult::LatexFormat);
         }
     }
 
 
     return result;
 }
 
 
 /*!
     example output for the simple expression '5+5':
     latex mode - "<cantor-result><cantor-text>\n(%o1) 10\n</cantor-text><cantor-latex>\\mbox{\\tt\\red(\\mathrm{\\%o1}) \\black}10</cantor-latex></cantor-result>\n<cantor-prompt>(%i2) </cantor-prompt>\n"
     text mode  - "<cantor-result><cantor-text>\n(%o1) 10\n</cantor-text></cantor-result>\n<cantor-prompt>(%i2) </cantor-prompt>\n"
  */
 bool MaximaExpression::parseOutput(QString& out)
 {
     const int promptStart = out.indexOf(QLatin1String("<cantor-prompt>"));
     const int promptEnd = out.indexOf(QLatin1String("</cantor-prompt>"));
     const QString prompt = out.mid(promptStart + 15, promptEnd - promptStart - 15).simplified();
 
     //check whether the result is part of the promt - this is the case when additional input is required from the user
     if (prompt.contains(QLatin1String("<cantor-result>")))
     {
         //text part of the output
         const int textContentStart = prompt.indexOf(QLatin1String("<cantor-text>"));
         const int textContentEnd = prompt.indexOf(QLatin1String("</cantor-text>"));
         QString textContent = prompt.mid(textContentStart + 13, textContentEnd - textContentStart - 13).trimmed();
 
         qDebug()<<"asking for additional input for " << textContent;
         emit needsAdditionalInformation(textContent);
         return true;
     }
 
     qDebug()<<"new input label: " << prompt;
 
     QString errorContent;
 
     //parse the results
     int resultStart = out.indexOf(QLatin1String("<cantor-result>"));
     if (resultStart != -1)
         errorContent += out.mid(0, resultStart);
     while (resultStart != -1)
     {
         int resultEnd = out.indexOf(QLatin1String("</cantor-result>"), resultStart + 15);
         const QString resultContent = out.mid(resultStart + 15, resultEnd - resultStart - 15);
         parseResult(resultContent);
 
         //search for the next openning <cantor-result> tag after the current closing </cantor-result> tag
         resultStart = out.indexOf(QLatin1String("<cantor-result>"), resultEnd + 16);
     }
 
     //parse the error message, the part outside of the <cantor*> tags
     int lastResultEnd = out.lastIndexOf(QLatin1String("</cantor-result>"));
     if (lastResultEnd != -1)
         lastResultEnd += 16;
     else
         lastResultEnd = 0;
 
     errorContent += out.mid(lastResultEnd, promptStart - lastResultEnd).trimmed();
     if (errorContent.isEmpty())
     {
         // For plots we set Done status in imageChanged
         if (!m_isPlot || m_plotResult)
             setStatus(Cantor::Expression::Done);
     }
     else
     {
         qDebug() << "error content: " << errorContent;
         if (out.contains(QLatin1String("cantor-value-separator")))
         {
             //when fetching variables, in addition to the actual result with variable names and values,
             //Maxima also write out the names of the variables to the error buffer.
             //we don't interpret this as an error.
             setStatus(Cantor::Expression::Done);
         }
         else if(m_isHelpRequest) //help messages are also part of the error output
         {
             Cantor::HelpResult* result = new Cantor::HelpResult(errorContent);
             addResult(result);
             setStatus(Cantor::Expression::Done);
         }
         else
         {
             errorContent = errorContent.replace(QLatin1String("\n\n"), QLatin1String("<br>"));
             errorContent = errorContent.replace(QLatin1String("\n"), QLatin1String("<br>"));
             setErrorMessage(errorContent);
             setStatus(Cantor::Expression::Error);
         }
     }
 
     return true;
 }
 
 void MaximaExpression::parseResult(const QString& resultContent)
 {
     qDebug()<<"result content: " << resultContent;
 
     //text part of the output
     const int textContentStart = resultContent.indexOf(QLatin1String("<cantor-text>"));
     const int textContentEnd = resultContent.indexOf(QLatin1String("</cantor-text>"));
     QString textContent = resultContent.mid(textContentStart + 13, textContentEnd - textContentStart - 13).trimmed();
     qDebug()<<"text content: " << textContent;
 
     //output label can be a part of the text content -> determine it
     const QRegExp regex = QRegExp(MaximaSession::MaximaOutputPrompt.pattern());
     const int index = regex.indexIn(textContent);
     QString outputLabel;
     if (index != -1) // No match, so output don't contain output label
         outputLabel = textContent.mid(index, regex.matchedLength()).trimmed();
     qDebug()<<"output label: " << outputLabel;
 
     //extract the expression id
     bool ok;
     QString idString = outputLabel.mid(3, outputLabel.length()-4);
     int id = idString.toInt(&ok);
     ok ? setId(id) : setId(-1);
     qDebug()<<"expression id: " << this->id();
 
     //remove the output label from the text content
     textContent = textContent.remove(outputLabel).trimmed();
 
     //determine the actual result
     Cantor::Result* result = nullptr;
 
     const int latexContentStart = resultContent.indexOf(QLatin1String("<cantor-latex>"));
     //Handle system maxima output for plotting commands
     if (m_isPlot && textContent.endsWith(QString::fromLatin1("\"%1\"]").arg(m_tempFile->fileName())))
     {
         m_plotResultIndex = results().size();
         // Gnuplot could generate plot before we parse text output from maxima and after
         // If we already have plot result, just add it
         // Else set info message, and replace it by real result in imageChanged function later
         if (m_plotResult)
             result = m_plotResult;
         else
             result = new Cantor::TextResult(i18n("Waiting for the plot result"));
     }
     else if (latexContentStart != -1)
     {
         //latex output is available
         const int latexContentEnd = resultContent.indexOf(QLatin1String("</cantor-latex>"));
         QString latexContent = resultContent.mid(latexContentStart + 14, latexContentEnd - latexContentStart - 14).trimmed();
         qDebug()<<"latex content: " << latexContent;
 
         Cantor::TextResult* textResult;
         //replace the \mbox{} environment, if available, by the eqnarray environment
         if (latexContent.indexOf(QLatin1String("\\mbox{")) != -1)
         {
             int i;
             int pcount=0;
             for(i = latexContent.indexOf(QLatin1String("\\mbox{"))+5; i < latexContent.size(); ++i)
             {
                 if(latexContent[i]==QLatin1Char('{'))
                     pcount++;
                 else if(latexContent[i]==QLatin1Char('}'))
                     pcount--;
 
                 if(pcount==0)
                     break;
             }
 
             QString modifiedLatexContent = latexContent.mid(i+1);
             if(modifiedLatexContent.trimmed().isEmpty())
             {
                 //empty content in the \mbox{} environment (e.g. for print() outputs), use the latex string outside of the \mbox{} environment
                 modifiedLatexContent = latexContent.left(latexContent.indexOf(QLatin1String("\\mbox{")));
             }
 
             modifiedLatexContent.prepend(QLatin1String("\\begin{eqnarray*}"));
             modifiedLatexContent.append(QLatin1String("\\end{eqnarray*}"));
             textResult = new Cantor::TextResult(modifiedLatexContent, textContent);
             qDebug()<<"modified latex content: " << modifiedLatexContent;
         }
         else
         {
             //no \mbox{} available, use what we've got.
             textResult = new Cantor::TextResult(latexContent, textContent);
         }
 
         textResult->setFormat(Cantor::TextResult::LatexFormat);
         result = textResult;
     }
     else
     {
         //no latex output is availabe, the actual result is part of the textContent string
         result = new Cantor::TextResult(textContent);
     }
 
     addResult(result);
 }
 
 void MaximaExpression::parseError(const QString& out)
 {
     m_errorBuffer.append(out);
 }
 
 void MaximaExpression::imageChanged()
 {
     if(m_tempFile->size()>0)
     {
 #ifdef WITH_EPS
         m_plotResult = new Cantor::EpsResult( QUrl::fromLocalFile(m_tempFile->fileName()) );
 #else
         m_plotResult = new Cantor::ImageResult( QUrl::fromLocalFile(m_tempFile->fileName()) );
 #endif
         // Check, that we already parse maxima output for this plot, and if not, keep it up to this moment
         // If it's true, replace text info result by real plot and set status as Done
         if (m_plotResultIndex != -1)
         {
             replaceResult(m_plotResultIndex, m_plotResult);
             setStatus(Cantor::Expression::Done);
         }
     }
 }
diff --git a/src/backends/maxima/maximaexpression.h b/src/backends/maxima/maximaexpression.h
index 517e273c..baefa600 100644
--- a/src/backends/maxima/maximaexpression.h
+++ b/src/backends/maxima/maximaexpression.h
@@ -1,74 +1,75 @@
 /*
     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>
  */
 
 #ifndef _MAXIMAEXPRESSION_H
 #define _MAXIMAEXPRESSION_H
 
 #include "expression.h"
 #include <QStringList>
 #include <QFileSystemWatcher>
 
 class QTemporaryFile;
 
 class MaximaExpression : public Cantor::Expression
 {
   Q_OBJECT
 
 public:
     explicit MaximaExpression(Cantor::Session*, bool internal = false);
+    ~MaximaExpression() override;
 
     void evaluate() override;
     void interrupt() override;
 
     void addInformation(const QString&) override;
 
     bool needsLatexResult();
 
     //returns the command that should be send to
     //the Maxima process, it's different from the
     //command() for example to allow plot embedding
     QString internalCommand();
 
     //Forces the status of this Expression to done
     void forceDone();
 
     //reads from @param out until a prompt indicates that a new expression has started
     bool parseOutput(QString&);
     bool parseOutputOld(QString&);
     void parseError(const QString&);
 
 private Q_SLOTS:
     void imageChanged();
 
 private:
     void parseResult(const QString&);
     Cantor::Result* parseResult(int* idx,QString& out,QString& textBuffer,QString& latexBuffer);
 
     QTemporaryFile *m_tempFile;
     QFileSystemWatcher m_fileWatch;
     bool m_isHelpRequest;
     bool m_isPlot;
     Cantor::Result* m_plotResult;
     int m_plotResultIndex;
     QString m_errorBuffer;
     bool m_gotErrorContent;
 };
 
 #endif /* _MAXIMAEXPRESSION_H */
diff --git a/src/backends/maxima/maximasession.cpp b/src/backends/maxima/maximasession.cpp
index 39cf330e..b822e5d4 100644
--- a/src/backends/maxima/maximasession.cpp
+++ b/src/backends/maxima/maximasession.cpp
@@ -1,347 +1,347 @@
 /*
     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
 
 
 MaximaSession::MaximaSession( Cantor::Backend* backend ) : Session(backend),
     m_process(nullptr),
     m_variableModel(new MaximaVariableModel(this)),
     m_justRestarted(false)
 {
 }
 
 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();
     m_process->waitForReadyRead();
     qDebug()<<m_process->readAllStandardOutput();
 
     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);
     }
 
     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;
 
     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::killLabels()
 {
     Cantor::Expression* e=evaluateExpression(QLatin1String("kill(labels);"), Cantor::Expression::DeleteOnFinish, true);
     //TODO: what for? connect(e, SIGNAL(statusChanged(Cantor::Expression::Status)), this, SIGNAL(ready()));
 }
 
 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();
     qDebug() << "expression status changed: command = " << expression->command() << ", status = " << status;
 
     if(status!=Cantor::Expression::Computing) //The session is ready for the next command
     {
         qDebug()<<"################################## EXPRESSION END ###############################################";
         disconnect(expression, SIGNAL(statusChanged(Cantor::Expression::Status)),
                    this, SLOT(currentExpressionChangedStatus(Cantor::Expression::Status)));
 
         expressionQueue().removeFirst();
         if(expressionQueue().isEmpty())
         {
             //if we are done with all the commands in the queue,
             //use the opportunity to update the variablemodel (if the last command wasn't already an update, as infinite loops aren't fun)
             QRegExp exp=QRegExp(QRegExp::escape(MaximaVariableModel::inspectCommand).arg(QLatin1String("(values|functions)")));
             QRegExp exp2=QRegExp(QRegExp::escape(MaximaVariableModel::variableInspectCommand).arg(QLatin1String("(values|functions)")));
 
             if(MaximaSettings::variableManagement()&&!exp.exactMatch(expression->command())&&!exp2.exactMatch(expression->command()))
             {
                 m_variableModel->checkForNewFunctions();
                 m_variableModel->checkForNewVariables();
             }else
             {
                 changeStatus(Cantor::Session::Done);
             }
 
         }else
         {
             runFirstExpression();
         }
     }
 }
 
 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
         }
         expressionQueue().first()->interrupt();
         expressionQueue().removeFirst();
         foreach (Cantor::Expression* expression, expressionQueue())
             expression->setStatus(Cantor::Expression::Done);
         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"));
-    Cantor::Expression* exp=evaluateExpression(QString::fromLatin1(":lisp(setf $display2d %1)").arg(val), Cantor::Expression::DeleteOnFinish, true);
+    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);
 }
 
 QAbstractItemModel* MaximaSession::variableModel()
 {
     return m_variableModel;
 }
 
 void MaximaSession::write(const QString& exp) {
     qDebug()<<"################################## EXPRESSION START ###############################################";
     qDebug()<<"sending expression to maxima process: " << exp;
     m_process->write(exp.toUtf8());
 }