diff --git a/src/libkstapp/changedatasampledialog.cpp b/src/libkstapp/changedatasampledialog.cpp
index b4d94f53..3d285b02 100644
--- a/src/libkstapp/changedatasampledialog.cpp
+++ b/src/libkstapp/changedatasampledialog.cpp
@@ -1,445 +1,449 @@
 /***************************************************************************
  *                                                                         *
  *   copyright : (C) 2007 The University of Toronto                        *
  *                   netterfield@astro.utoronto.ca                         *
  *                                                                         *
  *   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.                                   *
  *                                                                         *
  ***************************************************************************/
 
 #include "changedatasampledialog.h"
 
 #include "datacollection.h"
 #include "datavector.h"
 #include "datamatrix.h"
 #include "vscalar.h"
 #include "objectstore.h"
 #include "document.h"
 #include "mainwindow.h"
 #include "application.h"
 #include "dialogdefaults.h"
 #include "updatemanager.h"
 #include "updateserver.h"
 
 #include <QMessageBox>
 
 namespace Kst {
 
 ChangeDataSampleDialog::ChangeDataSampleDialog(QWidget *parent)
   : QDialog(parent) {
    setupUi(this);
 
   MainWindow::setWidgetFlags(this);
 
   if (MainWindow *mw = qobject_cast<MainWindow*>(parent)) {
     _store = mw->document()->objectStore();
   } else {
     // FIXME: we need the object store
     qFatal("ERROR: can't construct a ChangeDataSampleDialog without the object store");
   }
 
   connect(_add, SIGNAL(clicked()), this, SLOT(addButtonClicked()));
   connect(_remove, SIGNAL(clicked()), this, SLOT(removeButtonClicked()));
   connect(_removeAll, SIGNAL(clicked()), this, SLOT(removeAll()));
   connect(_addAll, SIGNAL(clicked()), this, SLOT(addAll()));
 
   connect(_vectorList, SIGNAL(itemDoubleClicked(QListWidgetItem*)), this, SLOT(availableDoubleClicked(QListWidgetItem*)));
   connect(_selectedVectorList, SIGNAL(itemDoubleClicked(QListWidgetItem*)), this, SLOT(selectedDoubleClicked(QListWidgetItem*)));
 
   connect(_vectorList, SIGNAL(itemSelectionChanged()), this, SLOT(updateButtons()));
   connect(_selectedVectorList, SIGNAL(itemSelectionChanged()), this, SLOT(updateButtons()));
 
   connect(_dataRange, SIGNAL(modified()), this, SLOT(modified()));
 
   connect(_buttonBox->button(QDialogButtonBox::Apply), SIGNAL(clicked()), this, SLOT(apply()));
   connect(_buttonBox->button(QDialogButtonBox::Ok), SIGNAL(clicked()), this, SLOT(OKClicked()));
   connect(_buttonBox->button(QDialogButtonBox::Cancel), SIGNAL(clicked()), this, SLOT(reject()));
   connect(UpdateServer::self(), SIGNAL(objectListsChanged()), this, SLOT(updateCurveListDialog()));
 
   initializeEntries();
   updateButtons();
   updateIndexEntries();
 
 }
 
 
 ChangeDataSampleDialog::~ChangeDataSampleDialog() {
 }
 
 
 void ChangeDataSampleDialog::show() {
   updateCurveListDialog();
   initializeEntries();
   updateButtons();
   QDialog::show();
 }
 
 
 void ChangeDataSampleDialog::removeButtonClicked() {
   foreach (QListWidgetItem* item, _selectedVectorList->selectedItems()) {
     _vectorList->addItem(_selectedVectorList->takeItem(_selectedVectorList->row(item)));
   }
 
   _vectorList->clearSelection();
   updateButtons();
   updateIndexEntries();
 
 }
 
 
 void ChangeDataSampleDialog::selectedDoubleClicked(QListWidgetItem * item) {
   if (item) {
     _vectorList->addItem(_selectedVectorList->takeItem(_selectedVectorList->row(item)));
     _vectorList->clearSelection();
     updateButtons();
     updateIndexEntries();
   }
 }
 
 
 void ChangeDataSampleDialog::addButtonClicked() {
   foreach (QListWidgetItem* item, _vectorList->selectedItems()) {
     _selectedVectorList->addItem(_vectorList->takeItem(_vectorList->row(item)));
   }
   _selectedVectorList->clearSelection();
   updateButtons();
   updateIndexEntries();
 }
 
 
 void ChangeDataSampleDialog::availableDoubleClicked(QListWidgetItem * item) {
   if (item) {
     _selectedVectorList->addItem(_vectorList->takeItem(_vectorList->row(item)));
     _selectedVectorList->clearSelection();
     updateButtons();
     updateIndexEntries();
   }
 }
 
 
 void ChangeDataSampleDialog::updateIndexEntries() {
 
   // Make a list of all the data sources for all of the vectors which have been selected.
   QList<DataSourcePtr> data_sources;
 
   _selectedVectorList->blockSignals(true);
   _selectedVectorList->selectAll();
   QList<QListWidgetItem*> selectedItems = _selectedVectorList->selectedItems();
   _selectedVectorList->clearSelection();
   _selectedVectorList->blockSignals(false);
 
   for (int i = 0; i < selectedItems.size(); ++i) {
     if (DataVectorPtr vector = kst_cast<DataVector>(_store->retrieveObject(selectedItems.at(i)->text()))) {
       if (!data_sources.contains(vector->dataSource())) {
         data_sources.append(vector->dataSource());
       }
     }
   }
 
   QStringList index_fields;
 
   // make a list of fields which are provided by all data sources...
   if (data_sources.size()>0) {
     foreach (const QString &field, data_sources[0]->indexFields()) {
       bool in_all = true;
       for (int i=1; i<data_sources.size(); i++) {
         in_all = in_all && (data_sources[i]->indexFields().contains(field));
       }
       if (in_all) {
         index_fields.append(field);
       }
     }
   }
 
   _dataRange->updateIndexList(index_fields);
 }
 
 
 void ChangeDataSampleDialog::updateButtons() {
   bool valid = _selectedVectorList->count() > 0;
   _buttonBox->button(QDialogButtonBox::Ok)->setEnabled(valid);
   _buttonBox->button(QDialogButtonBox::Apply)->setEnabled(valid);
   _add->setEnabled(_vectorList->selectedItems().count() > 0);
   _addAll->setEnabled(_vectorList->count() > 0);
   _remove->setEnabled(_selectedVectorList->selectedItems().count() > 0);
   _removeAll->setEnabled(_selectedVectorList->count() > 0);
 }
 
 
 void ChangeDataSampleDialog::modified() {
   updateButtons();
 }
 
 void ChangeDataSampleDialog::updateCurveListDialog() {
 
   PrimitiveList dataVectors = _store->getFramePrimitives();
   _vectorList->blockSignals(true);
 
   _vectorList->clearSelection();
   _selectedVectorList->clearSelection();
 
   // make sure all items in _vectorList exist in the store; remove if they don't.
   for (int i_item = 0; i_item < _vectorList->count(); i_item++) {
     bool exists=false;
     for (int i_vector = 0; i_vector<dataVectors.count(); i_vector++) {
       if (dataVectors.at(i_vector)->Name() == _vectorList->item(i_item)->text()) {
         exists = true;
         break;
       }
     }
     if (!exists) {
       QListWidgetItem *item = _vectorList->takeItem(i_item);
       delete item;
       i_item--;
     }
   }
 
   // make sure all items in _selectedVectorList exist in the store; remove if they don't.
   for (int i_item = 0; i_item<_selectedVectorList->count(); i_item++) {
     bool exists=false;
     for (int i_vector = 0; i_vector<dataVectors.count(); i_vector++) {
       if (dataVectors.at(i_vector)->Name() == _selectedVectorList->item(i_item)->text()) {
         exists = true;
         break;
       }
     }
     if (!exists) {
       QListWidgetItem *item = _selectedVectorList->takeItem(i_item);
       delete item;
       i_item--;
     }
   }
 
   // insert into _vectorList all items in store not in one of the lists.
   for (int i_vector = 0; i_vector<dataVectors.count(); i_vector++) {
     bool listed = false;
     for (int i_item = 0; i_item<_selectedVectorList->count(); i_item++) {
       if (dataVectors.at(i_vector)->Name() == _selectedVectorList->item(i_item)->text()) {
         _selectedVectorList->item(i_item)->setToolTip(dataVectors.at(i_vector)->descriptionTip());
         listed = true;
         break;
       }
     }
     for (int i_item = 0; i_item<_vectorList->count(); i_item++) {
       if (dataVectors.at(i_vector)->Name() == _vectorList->item(i_item)->text()) {
         _vectorList->item(i_item)->setToolTip(dataVectors.at(i_vector)->descriptionTip());
         listed = true;
         break;
       }
     }
     if (!listed) {
       QListWidgetItem *wi = new QListWidgetItem(dataVectors.at(i_vector)->Name());
       _vectorList->addItem(wi);
       wi->setToolTip(dataVectors.at(i_vector)->descriptionTip());
     }
   }
   _vectorList->blockSignals(false);
 }
 
 
 void ChangeDataSampleDialog::addAll() {
   _vectorList->selectAll();
   addButtonClicked();
 }
 
 
 void ChangeDataSampleDialog::removeAll() {
   _selectedVectorList->selectAll();
   removeButtonClicked();
 }
 
 
 void ChangeDataSampleDialog::initializeEntries() {
   _dataRange->setCountFromEnd(dialogDefaults().value("vector/countFromEnd",false).toBool());
   _dataRange->setStart(dialogDefaults().value("vector/start", 0).toInt());
   _dataRange->setReadToEnd(dialogDefaults().value("vector/readToEnd",true).toBool());
   _dataRange->setRange(dialogDefaults().value("vector/range", 1).toInt());
   _dataRange->setSkip(dialogDefaults().value("vector/skip", 0).toInt());
   _dataRange->setDoSkip(dialogDefaults().value("vector/doSkip", false).toBool());
   _dataRange->setDoFilter(dialogDefaults().value("vector/doAve",false).toBool());
   _dataRange->setStartUnits(dialogDefaults().value("vector/startUnits",tr("frames")).toString());
   _dataRange->setRangeUnits(dialogDefaults().value("vector/rangeUnits",tr("frames")).toString());
 }
 
 
 void ChangeDataSampleDialog::updateDefaults(QListWidgetItem* item) {
   if (!item) {
     return;
   }
 
   if (DataVectorPtr vector = kst_cast<DataVector>(_store->retrieveObject(item->text()))) {
     vector->readLock();
 
     _dataRange->setCountFromEnd(vector->countFromEOF());
     _dataRange->setStart(vector->countFromEOF() ? 0 : vector->reqStartFrame());
     _dataRange->setReadToEnd(vector->readToEOF());
     _dataRange->setRange(vector->readToEOF() ? 0 : vector->reqNumFrames());
     _dataRange->setSkip(vector->skip());
     _dataRange->setDoSkip(vector->doSkip());
     _dataRange->setDoFilter(vector->doAve());
 
     vector->unlock();
   }
 }
 
 
 void ChangeDataSampleDialog::OKClicked() {
   apply();
   accept();
 }
 
 
 void ChangeDataSampleDialog::apply() {
   _selectedVectorList->selectAll();
   QList<QListWidgetItem*> selectedItems = _selectedVectorList->selectedItems();
 
   QString start_units;
   QString range_units;
   QHash<QString, int> f0_map;
   QHash<QString, int> r_map;
   bool custom_start_index = (_dataRange->_startUnits->currentIndex() != 0) && (!_dataRange->countFromEnd());
 
   bool custom_range_index = (_dataRange->_rangeUnits->currentIndex() != 0) && (!_dataRange->readToEnd());
 
   if (!custom_start_index && !custom_range_index) { // FIXME: also for custom index.
     start_units.clear();
 
     // see if we have enough memory
     //FIXME: doesn't consider data objects that depend on this, and it should
     //FIXME: doesn't work under windows or mac
     double current_memory_used = 0.0;
     double memory_needed = 0.0;
     for (int i = 0; i < selectedItems.size(); ++i) {
       if (DataVectorPtr vector = kst_cast<DataVector>(_store->retrieveObject(selectedItems.at(i)->text()))) {
         current_memory_used += double(vector->length())*sizeof(double);
         long ns=0;
         if (_dataRange->readToEnd()) {
           ns = vector->fileLength() - (int)_dataRange->start();
         } else {
           ns = (int)_dataRange->range();
         }
         if (_dataRange->doSkip()) {
           ns/=_dataRange->skip();
         } else {
           ns *= vector->samplesPerFrame();
         }
         memory_needed += double(ns)*sizeof(double);
       }
     }
 
     double memory_available = Data::AvailableMemory();
     if (memory_needed-current_memory_used > memory_available) {
       //QApplication::restoreOverrideCursor();
       QMessageBox::warning(this, tr("Insufficient Memory"), tr("You requested to read in %1 MB of data but it seems that you only have approximately %2 MB of usable memory available.  You cannot load this much data."
                                                                    ).arg((memory_needed-current_memory_used)/(1024*1024)).arg(memory_available/(1024*1024)));
       return;
     }
   }
 
   start_units = _dataRange->_startUnits->currentText();
   range_units = _dataRange->_rangeUnits->currentText();
 
   for (int i = 0; i < selectedItems.size(); ++i) {
     QString filename;
     DataSourcePtr datasource;
     bool valid = false;
     bool use_custom_start_index = false;
     bool use_custom_range_index = false;
     if (DataVectorPtr vector = kst_cast<DataVector>(_store->retrieveObject(selectedItems.at(i)->text()))) {
       filename = vector->filename();
       datasource = vector->dataSource();
       valid = true;
       use_custom_range_index = custom_range_index;
       use_custom_start_index = custom_start_index;
     } else if (DataMatrixPtr matrix = kst_cast<DataMatrix>(_store->retrieveObject(selectedItems.at(i)->text()))) {
       filename = matrix->filename();
       datasource = matrix->dataSource();
       valid = true;
     } else if (VScalarPtr vscalar = kst_cast<VScalar>(_store->retrieveObject(selectedItems.at(i)->text()))) {
       filename = vscalar->filename();
       datasource = vscalar->dataSource();
       valid = true;
     }
     if (valid) {
       if (!f0_map.contains(filename)) {
         int f0;
         int r;
         if (use_custom_start_index) {
           f0 = datasource->indexToFrame(_dataRange->start(), start_units);
         } else if (_dataRange->countFromEnd()) {
           f0 = -1;
         } else {
           f0 = _dataRange->start();
         }
         if (use_custom_range_index) {
           r = _dataRange->range()*datasource->framePerIndex(range_units);
         } else if (_dataRange->readToEnd()) {
           r = -1;
         } else {
           r = (int)_dataRange->range();
         }
         f0_map.insert(filename, f0);
         r_map.insert(filename, r);
       }
     }
   }
 
   for (int i = 0; i < selectedItems.size(); ++i) {
     if (DataVectorPtr vector = kst_cast<DataVector>(_store->retrieveObject(selectedItems.at(i)->text()))) {
       vector->writeLock();
       int from = f0_map.value(vector->filename());
       int range = r_map.value(vector->filename());
       vector->changeFrames( from, 
                             range,
                             _dataRange->skip(),
                             _dataRange->doSkip(),
                             _dataRange->doFilter());
       vector->setStartUnits(start_units);
       vector->setRangeUnits(start_units);
       vector->registerChange();
       vector->unlock();
     } else if (DataMatrixPtr matrix = kst_cast<DataMatrix>(_store->retrieveObject(selectedItems.at(i)->text()))) {
       matrix->writeLock();
       int from = f0_map.value(matrix->filename());
       int range = r_map.value(matrix->filename());
-      matrix->setFrame(from+range-1);
+      if (from < 0) {
+        matrix->setFrame(-1);
+      } else {
+        matrix->setFrame(from+range-1);
+      }
       matrix->setStartUnits(start_units);
       matrix->setRangeUnits(start_units);
       matrix->registerChange();
       matrix->unlock();
     } else if (VScalarPtr vscalar = kst_cast<VScalar>(_store->retrieveObject(selectedItems.at(i)->text()))) {
       vscalar->writeLock();
       int from = f0_map.value(vscalar->filename());
       int range = r_map.value(vscalar->filename());
       vscalar->changeFrame(from+range-1);
       //vscalar->setStartUnits(start_units);
       //vscalar->setRangeUnits(start_units);
       vscalar->registerChange();
       vscalar->unlock();
     }
   }
 
   UpdateManager::self()->doUpdates(true);
   UpdateServer::self()->requestUpdateSignal();
 
   dialogDefaults().setValue("vector/range", _dataRange->range());
   dialogDefaults().setValue("vector/start", _dataRange->start());
   dialogDefaults().setValue("vector/countFromEnd", _dataRange->countFromEnd());
   dialogDefaults().setValue("vector/readToEnd", _dataRange->readToEnd());
   dialogDefaults().setValue("vector/skip", _dataRange->skip());
   dialogDefaults().setValue("vector/doSkip", _dataRange->doSkip());
   dialogDefaults().setValue("vector/doAve", _dataRange->doFilter());
   dialogDefaults().setValue("vector/startUnits", _dataRange->_startUnits->currentText());
   dialogDefaults().setValue("vector/rangeUnits", _dataRange->_rangeUnits->currentText());
 
   updateCurveListDialog();
   kstApp->mainWindow()->document()->setChanged(true);
 }
 
 
 }
 
 // vim: ts=2 sw=2 et