diff --git a/libs/widgets/KisPaletteModel.cpp b/libs/widgets/KisPaletteModel.cpp
index 464c7f0dba..43948f4aeb 100644
--- a/libs/widgets/KisPaletteModel.cpp
+++ b/libs/widgets/KisPaletteModel.cpp
@@ -1,511 +1,508 @@
 /*
  *  Copyright (c) 2013 Sven Langkamp <sven.langkamp@gmail.com>
  *  Copyright (c) 2018 Michael Zhou <simeirxh@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 "KisPaletteModel.h"
 
 #include <QBrush>
 #include <QDomDocument>
 #include <QDomElement>
 #include <QMimeData>
 
 #include <KoColor.h>
 
 #include <KoColorSpace.h>
 #include <KoColorModelStandardIds.h>
 #include <resources/KoColorSet.h>
 #include <KoColorDisplayRendererInterface.h>
 
 KisPaletteModel::KisPaletteModel(QObject* parent)
     : QAbstractTableModel(parent)
     , m_colorSet(0)
     , m_displayRenderer(KoDumbColorDisplayRenderer::instance())
 {
     connect(this, SIGNAL(sigPaletteModified()), SLOT(slotPaletteModified()));
 }
 
 KisPaletteModel::~KisPaletteModel()
 {
 }
 
 QVariant KisPaletteModel::data(const QModelIndex& index, int role) const
 {
     if (!index.isValid()) { return QVariant(); }
     bool groupNameRow = m_rowGroupNameMap.contains(index.row());
     if (role == IsGroupNameRole) {
         return groupNameRow;
     }
     if (groupNameRow) {
         return dataForGroupNameRow(index, role);
     } else {
         return dataForSwatch(index, role);
     }
 }
 
 int KisPaletteModel::rowCount(const QModelIndex& /*parent*/) const
 {
     if (!m_colorSet)
         return 0;
     return m_colorSet->rowCount() // count of color rows
             + m_rowGroupNameMap.size()  // rows for names
             - 1; // global doesn't have a name
 }
 
 int KisPaletteModel::columnCount(const QModelIndex& /*parent*/) const
 {
     if (m_colorSet && m_colorSet->columnCount() > 0) {
         return m_colorSet->columnCount();
     }
     if (!m_colorSet) {
         return 0;
     }
     return 16;
 }
 
 Qt::ItemFlags KisPaletteModel::flags(const QModelIndex& index) const
 {
     if (index.isValid()) {
         return  Qt::ItemIsSelectable |
                 Qt::ItemIsEnabled |
                 Qt::ItemIsUserCheckable |
                 Qt::ItemIsDragEnabled |
                 Qt::ItemIsDropEnabled;
     }
     return Qt::ItemIsDropEnabled;
 }
 
 QModelIndex KisPaletteModel::index(int row, int column, const QModelIndex& parent) const
 {
-    Q_UNUSED(parent);
+    Q_UNUSED(parent)
     Q_ASSERT(m_colorSet);
     int groupNameRow = groupNameRowForRow(row);
-    if (groupNameRow == -1) {
-        return {};
-    }
     KisSwatchGroup *group = m_colorSet->getGroup(m_rowGroupNameMap[groupNameRow]);
-    Q_ASSERT(group);
+    KIS_ASSERT_RECOVER_RETURN_VALUE(group,QModelIndex());
     return createIndex(row, column, group);
 }
 
 void KisPaletteModel::resetGroupNameRows()
 {
     m_rowGroupNameMap.clear();
     int row = -1;
     for (const QString &groupName : m_colorSet->getGroupNames()) {
         m_rowGroupNameMap[row] = groupName;
         row += m_colorSet->getGroup(groupName)->rowCount();
         row += 1; // row for group name
     }
 }
 
 void KisPaletteModel::setPalette(KoColorSet* palette)
 {
     beginResetModel();
     m_colorSet = palette;
     if (palette) {
         resetGroupNameRows();
     }
     endResetModel();
     emit sigPaletteChanged();
 }
 
 KoColorSet* KisPaletteModel::colorSet() const
 {
     return m_colorSet;
 }
 
 int KisPaletteModel::rowNumberInGroup(int rowInModel) const
 {
     if (m_rowGroupNameMap.contains(rowInModel)) {
         return -1;
     }
     QList<int> rowNumberList = m_rowGroupNameMap.keys();
     for (auto it = rowNumberList.rbegin(); it != rowNumberList.rend(); it++) {
         if (*it < rowInModel) {
             return rowInModel - *it - 1;
         }
     }
     return rowInModel;
 }
 
 int KisPaletteModel::groupNameRowForName(const QString &groupName)
 {
     for (auto it = m_rowGroupNameMap.begin(); it != m_rowGroupNameMap.end(); it++) {
         if (it.value() == groupName) {
             return it.key();
         }
     }
     return -1;
 }
 
 bool KisPaletteModel::addEntry(const KisSwatch &entry, const QString &groupName)
 {
     beginInsertRows(QModelIndex(), rowCount(), rowCount() + 1);
     m_colorSet->add(entry, groupName);
     endInsertRows();
     if (m_colorSet->isGlobal()) {
         m_colorSet->save();
     }
     emit sigPaletteModified();
     return true;
 }
 
 bool KisPaletteModel::removeEntry(const QModelIndex &index, bool keepColors)
 {
     if (!qvariant_cast<bool>(data(index, IsGroupNameRole))) {
         static_cast<KisSwatchGroup*>(index.internalPointer())->removeEntry(index.column(),
                                                                            rowNumberInGroup(index.row()));
         emit dataChanged(index, index);
     } else {
         int groupNameRow = groupNameRowForRow(index.row());
         QString groupName = m_rowGroupNameMap[groupNameRow];
         removeGroup(groupName, keepColors);
     }
     emit sigPaletteModified();
     return true;
 }
 
 void KisPaletteModel::removeGroup(const QString &groupName, bool keepColors)
 {
     int removeStart = groupNameRowForName(groupName);
     int removedRowCount = m_colorSet->getGroup(groupName)->rowCount();
     int insertStart = m_colorSet->getGlobalGroup()->rowCount();
     beginRemoveRows(QModelIndex(),
                     removeStart,
                     removeStart + removedRowCount);
     m_colorSet->removeGroup(groupName, keepColors);
     resetGroupNameRows();
     endRemoveRows();
     beginInsertRows(QModelIndex(),
 		    insertStart, m_colorSet->getGlobalGroup()->rowCount());
     endInsertRows();
     emit sigPaletteModified();
 }
 
 bool KisPaletteModel::dropMimeData(const QMimeData *data, Qt::DropAction action,
                                    int row, int column, const QModelIndex &parent)
 {
     Q_UNUSED(row);
     Q_UNUSED(column);
     if (!data->hasFormat("krita/x-colorsetentry") && !data->hasFormat("krita/x-colorsetgroup")) {
         return false;
     }
     if (action == Qt::IgnoreAction) {
         return false;
     }
 
     QModelIndex finalIndex = parent;
     if (!finalIndex.isValid()) { return false; }
 
     if (data->hasFormat("krita/x-colorsetgroup")) {
         // dragging group not supported for now
         QByteArray encodedData = data->data("krita/x-colorsetgroup");
         QDataStream stream(&encodedData, QIODevice::ReadOnly);
 
         while (!stream.atEnd()) {
             QString groupNameDroppedOn = qvariant_cast<QString>(finalIndex.data(GroupNameRole));
             if (groupNameDroppedOn == KoColorSet::GLOBAL_GROUP_NAME) {
                 return false;
             }
             QString groupNameDragged;
             stream >> groupNameDragged;
             KisSwatchGroup *groupDragged = m_colorSet->getGroup(groupNameDragged);
             int start = groupNameRowForName(groupNameDragged);
             int end = start + groupDragged->rowCount();
             if (!beginMoveRows(QModelIndex(), start, end, QModelIndex(), groupNameRowForName(groupNameDroppedOn))) {
                 return false;
             }
             m_colorSet->moveGroup(groupNameDragged, groupNameDroppedOn);
             resetGroupNameRows();
             endMoveRows();
             emit sigPaletteModified();
             if (m_colorSet->isGlobal()) {
                 m_colorSet->save();
             }
         }
         return true;
     }
 
     if (qvariant_cast<bool>(finalIndex.data(KisPaletteModel::IsGroupNameRole))) {
         return true;
     }
 
     QByteArray encodedData = data->data("krita/x-colorsetentry");
     QDataStream stream(&encodedData, QIODevice::ReadOnly);
 
     while (!stream.atEnd()) {
         KisSwatch entry;
 
         QString name, id;
         bool spotColor;
         QString oldGroupName;
         int oriRow;
         int oriColumn;
         QString colorXml;
 
         stream >> name >> id >> spotColor
                 >> oriRow >> oriColumn
                 >> oldGroupName
                 >> colorXml;
 
         entry.setName(name);
         entry.setId(id);
         entry.setSpotColor(spotColor);
 
         QDomDocument doc;
         doc.setContent(colorXml);
         QDomElement e = doc.documentElement();
         QDomElement c = e.firstChildElement();
         if (!c.isNull()) {
             QString colorDepthId = c.attribute("bitdepth", Integer8BitsColorDepthID.id());
             entry.setColor(KoColor::fromXML(c, colorDepthId));
         }
 
         if (action == Qt::MoveAction){
             KisSwatchGroup *g = m_colorSet->getGroup(oldGroupName);
             if (g) {
                 if (qvariant_cast<bool>(finalIndex.data(KisPaletteModel::CheckSlotRole))) {
                     g->setEntry(getEntry(finalIndex), oriColumn, oriRow);
                 } else {
                     g->removeEntry(oriColumn, oriRow);
                 }
             }
             setEntry(entry, finalIndex);
             emit sigPaletteModified();
             if (m_colorSet->isGlobal()) {
                 m_colorSet->save();
             }
         }
     }
 
     return true;
 }
 
 QMimeData *KisPaletteModel::mimeData(const QModelIndexList &indexes) const
 {
     QMimeData *mimeData = new QMimeData();
     QByteArray encodedData;
 
     QDataStream stream(&encodedData, QIODevice::WriteOnly);
     QModelIndex index = indexes.last();
     if (index.isValid() && qvariant_cast<bool>(index.data(CheckSlotRole))) {
         QString mimeTypeName = "krita/x-colorsetentry";
         if (qvariant_cast<bool>(index.data(IsGroupNameRole))==false) {
             KisSwatch entry = getEntry(index);
 
             QDomDocument doc;
             QDomElement root = doc.createElement("Color");
             root.setAttribute("bitdepth", entry.color().colorSpace()->colorDepthId().id());
             doc.appendChild(root);
             entry.color().toXML(doc, root);
 
             stream << entry.name() << entry.id() << entry.spotColor()
                    << rowNumberInGroup(index.row()) << index.column()
                    << qvariant_cast<QString>(index.data(GroupNameRole))
                    << doc.toString();
         } else {
             mimeTypeName = "krita/x-colorsetgroup";
             QString groupName = qvariant_cast<QString>(index.data(GroupNameRole));
             stream << groupName;
         }
         mimeData->setData(mimeTypeName, encodedData);
     }
 
     return mimeData;
 }
 
 QStringList KisPaletteModel::mimeTypes() const
 {
     return QStringList() << "krita/x-colorsetentry" << "krita/x-colorsetgroup";
 }
 
 Qt::DropActions KisPaletteModel::supportedDropActions() const
 {
     return Qt::MoveAction;
 }
 
 void KisPaletteModel::setEntry(const KisSwatch &entry,
                                const QModelIndex &index)
 {
     KisSwatchGroup *group = static_cast<KisSwatchGroup*>(index.internalPointer());
     Q_ASSERT(group);
     group->setEntry(entry, index.column(), rowNumberInGroup(index.row()));
     emit sigPaletteModified();
     emit dataChanged(index, index);
     if (m_colorSet->isGlobal()) {
         m_colorSet->save();
     }
 }
 
 bool KisPaletteModel::renameGroup(const QString &groupName, const QString &newName)
 {
     beginResetModel();
     bool success = m_colorSet->changeGroupName(groupName, newName);
     for (auto it = m_rowGroupNameMap.begin(); it != m_rowGroupNameMap.end(); it++) {
         if (it.value() == groupName) {
             m_rowGroupNameMap[it.key()] = newName;
             break;
         }
     }
     endResetModel();
     emit sigPaletteModified();
     return success;
 }
 
 void KisPaletteModel::addGroup(const KisSwatchGroup &group)
 {
     beginInsertRows(QModelIndex(), rowCount(), rowCount() + group.rowCount());
     m_colorSet->addGroup(group.name());
     *m_colorSet->getGroup(group.name()) = group;
     endInsertColumns();
 
     emit sigPaletteModified();
 }
 
 void KisPaletteModel::setRowNumber(const QString &groupName, int rowCount)
 {
     beginResetModel();
     KisSwatchGroup *g = m_colorSet->getGroup(groupName);
     if (g) {
         g->setRowCount(rowCount);
     }
     endResetModel();
 }
 
 void KisPaletteModel::clear()
 {
     beginResetModel();
     m_colorSet->clear();
     endResetModel();
 }
 
 QVariant KisPaletteModel::dataForGroupNameRow(const QModelIndex &idx, int role) const
 {
     KisSwatchGroup *group = static_cast<KisSwatchGroup*>(idx.internalPointer());
     Q_ASSERT(group);
     QString groupName = group->name();
     switch (role) {
     case Qt::ToolTipRole:
     case Qt::DisplayRole: {
         return groupName;
     }
     case GroupNameRole: {
         return groupName;
     }
     case CheckSlotRole: {
         return true;
     }
     case RowInGroupRole: {
         return -1;
     }
     default: {
         return QVariant();
     }
     }
 }
 
 QVariant KisPaletteModel::dataForSwatch(const QModelIndex &idx, int role) const
 {
     KisSwatchGroup *group = static_cast<KisSwatchGroup*>(idx.internalPointer());
     Q_ASSERT(group);
     int rowInGroup = rowNumberInGroup(idx.row());
     bool entryPresent = group->checkEntry(idx.column(), rowInGroup);
     KisSwatch entry;
     if (entryPresent) {
         entry = group->getEntry(idx.column(), rowInGroup);
     }
     switch (role) {
     case Qt::ToolTipRole:
     case Qt::DisplayRole: {
         return entryPresent ? entry.name() : i18n("Empty slot");
     }
     case Qt::BackgroundRole: {
         QColor color(0, 0, 0, 0);
         if (entryPresent) {
             color = m_displayRenderer->toQColor(entry.color());
         }
         return QBrush(color);
     }
     case GroupNameRole: {
         return group->name();
     }
     case CheckSlotRole: {
         return entryPresent;
     }
     case RowInGroupRole: {
         return rowInGroup;
     }
     default: {
         return QVariant();
     }
     }
 }
 
 void KisPaletteModel::setDisplayRenderer(const KoColorDisplayRendererInterface *displayRenderer)
 {
     if (displayRenderer) {
         if (m_displayRenderer) {
             disconnect(m_displayRenderer, 0, this, 0);
         }
         m_displayRenderer = displayRenderer;
         connect(m_displayRenderer, SIGNAL(displayConfigurationChanged()),
                 SLOT(slotDisplayConfigurationChanged()), Qt::UniqueConnection);
     } else {
         m_displayRenderer = KoDumbColorDisplayRenderer::instance();
     }
 }
 
 void KisPaletteModel::slotDisplayConfigurationChanged()
 {
     beginResetModel();
     endResetModel();
 }
 
 void KisPaletteModel::slotPaletteModified() {
     m_colorSet->setPaletteType(KoColorSet::KPL);
 }
 
 QModelIndex KisPaletteModel::indexForClosest(const KoColor &compare)
 {
     KisSwatchGroup::SwatchInfo info = colorSet()->getClosestColorInfo(compare);
     return createIndex(indexRowForInfo(info), info.column, colorSet()->getGroup(info.group));
 }
 
 int KisPaletteModel::indexRowForInfo(const KisSwatchGroup::SwatchInfo &info)
 {
     for (auto it = m_rowGroupNameMap.begin(); it != m_rowGroupNameMap.end(); it++) {
         if (it.value() == info.group) {
             return it.key() + info.row + 1;
         }
     }
     return info.row;
 }
 
 KisSwatch KisPaletteModel::getEntry(const QModelIndex &index) const
 {
     KisSwatchGroup *group = static_cast<KisSwatchGroup*>(index.internalPointer());
     if (!group || !group->checkEntry(index.column(), rowNumberInGroup(index.row()))) {
         return KisSwatch();
     }
     return group->getEntry(index.column(), rowNumberInGroup(index.row()));
 }
 
 int KisPaletteModel::groupNameRowForRow(int rowInModel) const
 {
     return rowInModel - rowNumberInGroup(rowInModel) - 1;
 }