diff --git a/libs/ui/KisChangeCloneLayersCommand.cpp b/libs/ui/KisChangeCloneLayersCommand.cpp
index bbec880008..2d8c29a75d 100644
--- a/libs/ui/KisChangeCloneLayersCommand.cpp
+++ b/libs/ui/KisChangeCloneLayersCommand.cpp
@@ -1,58 +1,70 @@
 /*
  *  Copyright (c) 2019 Tusooa Zhu <tusooa@vista.aero>
  *
  *  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 "KisChangeCloneLayersCommand.h"
 
 #include <kis_clone_layer.h>
 
 struct KisChangeCloneLayersCommand::Private
 {
     QList<KisCloneLayerSP> cloneLayers;
     QList<KisLayerSP> originalSource;
     KisLayerSP newSource;
 };
 
 KisChangeCloneLayersCommand::KisChangeCloneLayersCommand(QList<KisCloneLayerSP> cloneLayers, KisLayerSP newSource, KUndo2Command *parent)
     : KUndo2Command(kundo2_i18n("Change Clone Layers"), parent)
     , d(new Private())
 {
     KIS_SAFE_ASSERT_RECOVER_RETURN(!cloneLayers.isEmpty());
     d->cloneLayers = cloneLayers;
     Q_FOREACH (KisCloneLayerSP layer, d->cloneLayers) {
         d->originalSource << layer->copyFrom();
     }
     d->newSource = newSource;
 }
 
 void KisChangeCloneLayersCommand::redo()
 {
     Q_FOREACH (KisCloneLayerSP layer, d->cloneLayers) {
         layer->setCopyFrom(d->newSource);
         layer->setDirty();
     }
 }
 
 void KisChangeCloneLayersCommand::undo()
 {
     KIS_SAFE_ASSERT_RECOVER_RETURN(d->cloneLayers.size() == d->originalSource.size());
     for (int i = 0; i < d->cloneLayers.size(); ++i) {
         KisCloneLayerSP layer = d->cloneLayers.at(i);
         layer->setCopyFrom(d->originalSource.at(i));
         layer->setDirty();
     }
 }
+
+bool KisChangeCloneLayersCommand::mergeWith(const KUndo2Command *command)
+{
+    const KisChangeCloneLayersCommand *other = dynamic_cast<const KisChangeCloneLayersCommand *>(command);
+
+    if (other && d->cloneLayers == other->d->cloneLayers) {
+        d->newSource = other->d->newSource;
+        return true;
+    }
+
+    return false;
+}
diff --git a/libs/ui/KisChangeCloneLayersCommand.h b/libs/ui/KisChangeCloneLayersCommand.h
index 465a84d81a..3e0308b95b 100644
--- a/libs/ui/KisChangeCloneLayersCommand.h
+++ b/libs/ui/KisChangeCloneLayersCommand.h
@@ -1,39 +1,40 @@
 /*
  *  Copyright (c) 2019 Tusooa Zhu <tusooa@vista.aero>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
 #ifndef KIS_CHANGE_CLONE_LAYERS_COMMAND_H_
 #define KIS_CHANGE_CLONE_LAYERS_COMMAND_H_
 
 #include <kundo2command.h>
 #include "kis_types.h"
 
 class KisChangeCloneLayersCommand : public KUndo2Command
 {
 
 public:
     KisChangeCloneLayersCommand(QList<KisCloneLayerSP> cloneLayers, KisLayerSP newSource, KUndo2Command *parent = 0);
 
     void undo() override;
     void redo() override;
+    bool mergeWith(const KUndo2Command *) override;
 
 private:
     struct Private;
     QScopedPointer<Private> d;
 };
 
 #endif // KIS_CHANGE_CLONE_LAYERS_COMMAND_H_
diff --git a/libs/ui/dialogs/KisDlgChangeCloneSource.cpp b/libs/ui/dialogs/KisDlgChangeCloneSource.cpp
index c878b08d34..12acf01bcd 100644
--- a/libs/ui/dialogs/KisDlgChangeCloneSource.cpp
+++ b/libs/ui/dialogs/KisDlgChangeCloneSource.cpp
@@ -1,234 +1,193 @@
 /*
  *  Copyright (c) 2019 Tusooa Zhu <tusooa@vista.aero>
  *
  *  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 "KisDlgChangeCloneSource.h"
 
 #include <kis_clone_layer.h>
 #include <kis_image.h>
 #include <kis_undo_adapter.h>
 #include <kis_processing_applicator.h>
 #include <KisImageSignals.h>
+#include <kis_signals_blocker.h>
 
 #include "KisViewManager.h"
 #include "KisChangeCloneLayersCommand.h"
 
 struct KisDlgChangeCloneSource::Private
 {
+    Private(QList<KisCloneLayerSP> layers, KisViewManager *view)
+        : cloneLayers(layers)
+        , view(view)
+        , image(view->image())
+        , applicator(new KisProcessingApplicator(image, 0,
+                                                       KisProcessingApplicator::NONE,
+                                                       /* emitSignals */ KisImageSignalVector() << ModifiedSignal,
+                                                       kundo2_i18n("Change Clone Layers")))
+        , lastCommand(0) {}
+
     QList<KisCloneLayerSP> cloneLayers;
     KisViewManager *view;
     KisImageSP image;
     QList<KisLayerSP> validTargets;
     Ui::WdgChangeCloneSource ui;
-    KisNodeSP rootNode;
-    KisProcessingApplicator *applicator;
+    QScopedPointer<KisProcessingApplicator> applicator;
     KUndo2Command *lastCommand;
-    bool canUpdateApplicator;
 
     void addToTargetListRecursively(KisNodeSP node, bool addSelf = true);
     void filterOutAncestorsAndClonesRecursively(KisLayerSP layer);
-    void createApplicator();
     KisLayerSP getSelectedTargetLayer();
     KUndo2Command *createCommand(KisLayerSP targetLayer);
 };
 
 void KisDlgChangeCloneSource::Private::addToTargetListRecursively(KisNodeSP node, bool addSelf)
 {
     if (!node) {
         return;
     }
     if (addSelf) {
         KisLayerSP layer(qobject_cast<KisLayer *>(node.data()));
         if (layer) {
             validTargets << layer;
         }
     }
     for (KisNodeSP childNode = node->lastChild(); childNode; childNode = childNode->prevSibling()) {
         KisLayerSP childLayer(qobject_cast<KisLayer *>(childNode.data()));
         if (childLayer) {
             addToTargetListRecursively(childLayer);
         }
     }
 
 }
 
 void KisDlgChangeCloneSource::Private::filterOutAncestorsAndClonesRecursively(KisLayerSP layer)
 {
     validTargets.removeOne(layer);
     // remove `layer` and its ancestors
     KisLayerSP parent = qobject_cast<KisLayer *>(layer->parent().data());
     if (parent) {
         filterOutAncestorsAndClonesRecursively(parent);
     }
 
     // remove all clones of `layer`, and their ancestors
     Q_FOREACH (KisCloneLayerSP clone, layer->registeredClones()) {
         filterOutAncestorsAndClonesRecursively(clone);
     }
 }
 
-void KisDlgChangeCloneSource::Private::createApplicator()
-{
-    delete applicator;
-
-    KisImageSignalVector emitSignals;
-    emitSignals << ModifiedSignal;
-
-    applicator = new KisProcessingApplicator(image, 0,
-                                             KisProcessingApplicator::NONE,
-                                             emitSignals,
-                                             kundo2_i18n("Change Clone Layers"));
-}
-
 KisLayerSP KisDlgChangeCloneSource::Private::getSelectedTargetLayer()
 {
     int index = ui.cmbSourceLayer->currentIndex();
     if (index != -1) {
         return validTargets.at(index);
     } else {
         return 0;
     }
 }
 
 KUndo2Command *KisDlgChangeCloneSource::Private::createCommand(KisLayerSP targetLayer)
 {
     lastCommand = new KisChangeCloneLayersCommand(cloneLayers, targetLayer);
     return lastCommand;
 }
 
 KisDlgChangeCloneSource::KisDlgChangeCloneSource(QList<KisCloneLayerSP> layers, KisViewManager *view, QWidget *parent)
     : KoDialog(parent)
-    , d(new Private())
+    , d(new Private(layers, view))
 {
     KIS_SAFE_ASSERT_RECOVER_RETURN(!layers.isEmpty());
-    d->cloneLayers = layers;
-    d->view = view;
-    d->image = d->view->image();
-    d->createApplicator();
-    d->canUpdateApplicator = false;
-
-    connect(d->image, &KisImage::sigStrokeCancellationRequested,
-            this, &KisDlgChangeCloneSource::closeAndReject);
-    connect(d->image, &KisImage::sigUndoDuringStrokeRequested,
-            this, &KisDlgChangeCloneSource::closeAndReject);
-    connect(d->image, &KisImage::sigStrokeEndRequested,
-            this, &KisDlgChangeCloneSource::closeAndAccept);
-
-    connect(this, &KisDlgChangeCloneSource::accepted,
-            this, &KisDlgChangeCloneSource::slotEndOrUndoChanges);
-    connect(this, &KisDlgChangeCloneSource::rejected,
-            this, &KisDlgChangeCloneSource::slotEndOrUndoChanges);
+
+    connect(d->image.data(), &KisImage::sigStrokeCancellationRequested,
+            this, &KisDlgChangeCloneSource::reject);
+    connect(d->image.data(), &KisImage::sigUndoDuringStrokeRequested,
+            this, &KisDlgChangeCloneSource::reject);
+    connect(d->image.data(), &KisImage::sigStrokeEndRequested,
+            this, &KisDlgChangeCloneSource::accept);
 
     setButtons(Ok | Cancel);
     setDefaultButton(Ok);
 
     QWidget *widget = new QWidget(this);
     d->ui.setupUi(widget);
     setMainWidget(widget);
 
     connect(d->ui.cmbSourceLayer, QOverload<int>::of(&QComboBox::currentIndexChanged),
             this, &KisDlgChangeCloneSource::slotCancelChangesAndSetNewTarget);
 
     updateTargetLayerList();
 }
 
 KisDlgChangeCloneSource::~KisDlgChangeCloneSource()
 {
     dbgUI << "dialog destroyed";
-    delete d->applicator;
+    if (d->applicator) {
+        if (result() == QDialog::Accepted && d->lastCommand) {
+            dbgUI << "Accepted";
+            d->applicator->end();
+        } else { // if the user never changed it, no need to make another undo command
+            dbgUI << "Rejected";
+            d->applicator->cancel();
+        }
+    }
 }
 
 void KisDlgChangeCloneSource::updateTargetLayerList()
 {
-    KisImageWSP image = d->view->image();
+    KisSignalsBlocker b(d->ui.cmbSourceLayer);
+
+    KisImageSP image = d->image;
     if (!image) {
         return;
     }
     KisNodeSP root = image->root();
-    d->rootNode = root;
     d->validTargets.clear();
     d->addToTargetListRecursively(root, /* addSelf = */ false);
 
     KisLayerSP commonCopyFrom(d->cloneLayers.first()->copyFrom());
 
     Q_FOREACH (KisCloneLayerSP clone, d->cloneLayers) {
         // filter out invalid targets:
         // selected clone layers, their ancestors;
         // the clone layers' registered clone, the clones' ancestors.
         d->filterOutAncestorsAndClonesRecursively(clone);
 
         // assume that clone->copyFrom() != 0
         if (clone->copyFrom() != commonCopyFrom) {
             commonCopyFrom = 0;
         }
     }
 
     d->ui.cmbSourceLayer->clear();
     Q_FOREACH (KisNodeSP node, d->validTargets) {
         d->ui.cmbSourceLayer->addItem(node->name());
     }
 
-    d->canUpdateApplicator = false;
-
     if (commonCopyFrom) {
         d->ui.cmbSourceLayer->setCurrentIndex(d->validTargets.indexOf(commonCopyFrom));
     } else {
         d->ui.cmbSourceLayer->setCurrentIndex(-1);
     }
-
-    d->canUpdateApplicator = true;
 }
 
 void KisDlgChangeCloneSource::slotCancelChangesAndSetNewTarget()
 {
-    // if lastCommand is empty, it means the user never selected a target
-    if (d->lastCommand) {
-        d->applicator->cancel();
-        d->createApplicator();
-    }
-    if (d->canUpdateApplicator) {
-        KisLayerSP targetLayer = d->getSelectedTargetLayer();
-        if (targetLayer) {
-            d->applicator->applyCommand(d->createCommand(targetLayer));
-        }
-    }
-}
-
-void KisDlgChangeCloneSource::slotEndOrUndoChanges()
-{
-    disconnect(this, &KisDlgChangeCloneSource::accepted,
-               this, &KisDlgChangeCloneSource::slotEndOrUndoChanges);
-    disconnect(this, &KisDlgChangeCloneSource::rejected,
-               this, &KisDlgChangeCloneSource::slotEndOrUndoChanges);
-    if (result() == QDialog::Accepted && d->lastCommand) {
-        dbgUI << "Accepted";
-        d->applicator->end();
-    } else { // if the user never changed it, no need to make another undo command
-        dbgUI << "Rejected";
-        d->applicator->cancel();
+    KisLayerSP targetLayer = d->getSelectedTargetLayer();
+    if (targetLayer) {
+        d->applicator->applyCommand(d->createCommand(targetLayer));
     }
 }
 
-void KisDlgChangeCloneSource::closeAndAccept()
-{
-    done(QDialog::Accepted);
-}
-
-void KisDlgChangeCloneSource::closeAndReject()
-{
-    done(QDialog::Rejected);
-}
diff --git a/libs/ui/dialogs/KisDlgChangeCloneSource.h b/libs/ui/dialogs/KisDlgChangeCloneSource.h
index eb0e601f2b..3957a40d6e 100644
--- a/libs/ui/dialogs/KisDlgChangeCloneSource.h
+++ b/libs/ui/dialogs/KisDlgChangeCloneSource.h
@@ -1,53 +1,50 @@
 /*
  *  Copyright (c) 2019 Tusooa Zhu <tusooa@vista.aero>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  */
 
 #ifndef KIS_DLG_CHANGE_CLONE_SOURCE_H_
 #define KIS_DLG_CHANGE_CLONE_SOURCE_H_
 
 #include "kis_types.h"
 #include <KoDialog.h>
 
 #include "ui_wdgchangeclonesource.h"
 
 class QWidget;
 class KisViewManager;
 
 class KisDlgChangeCloneSource : public KoDialog
 {
     Q_OBJECT
 
 public:
     KisDlgChangeCloneSource(QList<KisCloneLayerSP> layers, KisViewManager *view, QWidget *parent = 0);
 
     ~KisDlgChangeCloneSource() override;
 
 private:
     void updateTargetLayerList();
 
-private Q_SLOTS:
+public Q_SLOTS:
     void slotCancelChangesAndSetNewTarget();
-    void slotEndOrUndoChanges();
-    void closeAndAccept();
-    void closeAndReject();
 
 private:
     struct Private;
     const QScopedPointer<Private> d;
 };
 
 #endif // KIS_DLG_CHANGE_CLONE_SOURCE_H_