Multiselect refactoring

Now store multiselection status and list on c++ side only to
reduce problems from keeping them properly synchronized.

Change-Id: If3277bb1eca5ffc7a7749e300e0cc6de4ccf9df2
Reviewed-by: Titta Heikkala <titta.heikkala@qt.io>
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>

9 files changed, 243 insertions, 224 deletions

diff --git a/editorlib/qml/ComponentMenu.qml b/editorlib/qml/ComponentMenu.qml
index 63ce969..8a00107 100644
--- a/editorlib/qml/ComponentMenu.qml
+++ b/editorlib/qml/ComponentMenu.qml
@@ -67,7 +67,7 @@ Menu {
     MenuItem {
         text: qsTr("Object Picker") + editorScene.emptyString
         iconSource: "images/picker.png"
-        enabled: !entityTree.multiSelect
+        enabled: !editorScene.multiSelection
         onTriggered: {
             componentPropertiesView.model.appendNewComponent(sceneModel.ObjectPicker)
         }
@@ -77,7 +77,7 @@ Menu {
 
     EntityMenu {
         iconSource: "images/plus.png"
-        enabled: !entityTree.multiSelect && !entityTreeView.cameraSelected
+        enabled: !editorScene.multiSelection && !entityTreeView.cameraSelected
     }
     MenuItem {
         text: qsTr("Remove") + editorScene.emptyString
@@ -85,13 +85,14 @@ Menu {
         iconSource: "images/minus.png"
         onTriggered: {
             entityTreeView.editing = false
-            if (entityTree.multiSelect) {
+            if (editorScene.multiSelection) {
                 // Handle multiselection removal
                 editorScene.undoHandler.beginMacro(text)
-                var removeList = editorScene.sceneModel.parentList(selectionList)
+                var removeList = editorScene.sceneModel.parentList(editorScene.multiSelectionList)
                 for (var i = 0; i < removeList.length; ++i)
                     editorScene.undoHandler.createRemoveEntityCommand(removeList[i])
                 editorScene.undoHandler.endMacro()
+                entityTree.selectSceneRoot()
             } else {
                 // Doublecheck that we don't try to remove the scene root
                 if (entityTreeView.selection.currentIndex !== editorScene.sceneModel.sceneEntityIndex())
@@ -104,13 +105,14 @@ Menu {
         enabled: !entityTreeView.sceneRootSelected
         iconSource: "images/duplicate.png"
         onTriggered: {
-            if (entityTree.multiSelect) {
+            if (editorScene.multiSelection) {
                 // Handle multiselection duplication
                 editorScene.undoHandler.beginMacro(text)
-                var duplicateList = editorScene.sceneModel.parentList(selectionList)
+                var duplicateList = editorScene.sceneModel.parentList(editorScene.multiSelectionList)
                 for (var i = 0; i < duplicateList.length; ++i)
                     editorScene.undoHandler.createDuplicateEntityCommand(duplicateList[i])
                 editorScene.undoHandler.endMacro()
+                editorScene.restoreMultiSelection(editorScene.multiSelectionList)
             } else {
                 var currentSelection = selectedEntity.entity()
                 editorScene.undoHandler.createDuplicateEntityCommand(selectedEntityName)
@@ -120,7 +122,7 @@ Menu {
     }
     MenuItem {
         text: qsTr("Copy (Ctrl + c)") + editorScene.emptyString
-        enabled: !entityTree.multiSelect && !entityTreeView.sceneRootSelected
+        enabled: !editorScene.multiSelection && !entityTreeView.sceneRootSelected
         iconSource: "images/copy.png"
         onTriggered: {
             mainwindow.copyEntity(selectedEntityName)
@@ -128,7 +130,7 @@ Menu {
     }
     MenuItem {
         text: qsTr("Cut (Ctrl + x)") + editorScene.emptyString
-        enabled: !entityTree.multiSelect && !entityTreeView.sceneRootSelected
+        enabled: !editorScene.multiSelection && !entityTreeView.sceneRootSelected
         iconSource: "images/cut.png"
         onTriggered: {
             mainwindow.cutEntity(selectedEntityName, selectedEntity)
@@ -136,7 +138,7 @@ Menu {
     }
     MenuItem {
         text: qsTr("Paste (Ctrl + v)") + editorScene.emptyString
-        enabled: trackMousePosition && !entityTree.multiSelect
+        enabled: trackMousePosition && !editorScene.multiSelection
                  && (!entityTree.treeviewPasting || (entityTree.treeviewPasting
                                                      && editorScene.sceneModel.canReparent(
                          editorScene.sceneModel.editorSceneItemFromIndex(
@@ -153,7 +155,7 @@ Menu {
     MenuItem {
         text: qsTr("Reset") + editorScene.emptyString
         iconSource: "images/reset_all.png"
-        enabled: !entityTree.multiSelect && !entityTreeView.sceneRootSelected
+        enabled: !editorScene.multiSelection && !entityTreeView.sceneRootSelected
         onTriggered: {
             editorScene.undoHandler.createResetEntityCommand(selectedEntityName)
         }
@@ -161,7 +163,7 @@ Menu {
     MenuItem {
         text: qsTr("Reset Transform") + editorScene.emptyString
         iconSource: "images/reset.png"
-        enabled: !entityTree.multiSelect && !entityTreeView.sceneRootSelected
+        enabled: !editorScene.multiSelection && !entityTreeView.sceneRootSelected
                  && !entityTreeView.cameraSelected
         onTriggered: {
             editorScene.undoHandler.createResetTransformCommand(selectedEntityName)
@@ -176,8 +178,8 @@ Menu {
             // Copy list, as the original is emptied on insertEntity
             var reparentList = []
             var groupCenter
-            if (entityTree.multiSelect) {
-                reparentList = editorScene.sceneModel.parentList(selectionList)
+            if (editorScene.multiSelection) {
+                reparentList = editorScene.sceneModel.parentList(editorScene.multiSelectionList)
                 groupCenter = editorScene.getMultiSelectionCenter()
             } else {
                 reparentList[0] = selectedEntityName
@@ -186,10 +188,6 @@ Menu {
 
             // TODO: Allow creating groups under other entities?
 
-            // Select scene root before doing reparenting to avoid having selection changes
-            // while removing, as indexes can be corrupt during the removal
-            entityTree.selectSceneRoot()
-
             // Add new group
             editorScene.undoHandler.createInsertEntityCommand(1, editorScene.sceneRootName(),
                                                               groupCenter)
@@ -199,11 +197,11 @@ Menu {
             for (var i = 0; i < reparentList.length; ++i)
                 editorScene.undoHandler.createReparentEntityCommand(groupName, reparentList[i])
             editorScene.undoHandler.endMacro()
-            // Clear selection
-            entityTree.multiSelect = false
-            editorScene.multiSelection = []
-            // Select the added group
-            editorScene.selectIndex(index)
+
+            // Single-select the added group. Need to fetch group index again as reparenting
+            // resets the model.
+            editorScene.clearMultiSelection()
+            editorScene.selectIndex(editorScene.sceneModel.getModelIndexByName(groupName))
         }
     }
 }
diff --git a/editorlib/qml/EntityTree.qml b/editorlib/qml/EntityTree.qml
index 4a726e2..3edb985 100644
--- a/editorlib/qml/EntityTree.qml
+++ b/editorlib/qml/EntityTree.qml
@@ -40,17 +40,16 @@ Item {
     property alias view: entityTreeView
     property alias menu: addComponentMenu
     property bool treeviewPasting: false
-    property bool multiSelect: false
-    property bool multiSelectedCamera: false
 
     Keys.onDeletePressed: {
-        if (multiSelect) {
+        if (editorScene.multiSelection) {
             // Handle multiselection removal
             editorScene.undoHandler.beginMacro("Remove selected")
-            var removeList = editorScene.sceneModel.parentList(selectionList)
+            var removeList = editorScene.sceneModel.parentList(editorScene.multiSelectionList)
             for (var i = 0; i < removeList.length; ++i)
                 editorScene.undoHandler.createRemoveEntityCommand(removeList[i])
             editorScene.undoHandler.endMacro()
+            selectSceneRoot()
         } else {
             // Doublecheck that we don't try to remove the scene root
             if (entityTreeView.selection.currentIndex !== editorScene.sceneModel.sceneEntityIndex())
@@ -63,6 +62,7 @@ Item {
     }
 
     function selectSceneRoot() {
+        editorScene.clearMultiSelection()
         entityTreeView.selection.setCurrentIndex(
                     editorScene.sceneModel.sceneEntityIndex(),
                     ItemSelectionModel.SelectCurrent)
@@ -74,6 +74,8 @@ Item {
         var y = yPos ? yPos : -1
         entityTreeView.editing = false
 
+        editorScene.clearMultiSelection()
+
         // Never allow inserting to root
         if (entityTreeView.selection.currentIndex.row === -1)
             selectSceneRoot()
@@ -218,21 +220,16 @@ Item {
                 onPressed: {
                     if (mouse.modifiers & Qt.ControlModifier) {
                         // Handle multiselection
-                        // Prevent multiselecting scene root
-                        if (styleData.index !== editorScene.sceneModel.sceneEntityIndex()) {
-                            editorScene.addToMultiSelection(editorScene.sceneModel.entityName(
-                                                                styleData.index))
-                        }
-                        // If empty list, select scene root
-                        if (selectionList.length === 0) {
-                            selectedEntityName = ""
-                            selectSceneRoot()
+                        // Prevent multiselecting scene root and toggling when singly selected
+                        // entity is clicked again
+                        if ((editorScene.multiSelection
+                                || styleData.index !== entityTreeView.selection.currentIndex)
+                                && styleData.index !== editorScene.sceneModel.sceneEntityIndex()) {
+                            editorScene.toggleEntityMultiSelection(editorScene.sceneModel.entityName(
+                                                                       styleData.index))
                         }
                     } else {
-                        // Clear selectionList
-                        entityTreeView.selection.clear()
-                        selectionList.length = 0
-                        editorScene.multiSelection = selectionList
+                        editorScene.clearMultiSelection()
                         entityTreeView.selection.setCurrentIndex(styleData.index,
                                                                  ItemSelectionModel.SelectCurrent)
                     }
@@ -295,6 +292,7 @@ Item {
                 onDropped: {
                     if (isValidDropTarget(drop.source)) {
                         dragHighlight.visible = false
+                        editorScene.clearMultiSelection()
                         entityTreeView.selection.setCurrentIndex(styleData.index,
                                                                  ItemSelectionModel.SelectCurrent)
                         if (drop.source.drag.target.dragKey === "changeParent") {
@@ -432,14 +430,12 @@ Item {
             target: entityTreeView.selection
             onCurrentIndexChanged: {
                 entityTreeView.editing = false
-                // If there is no current item selected for some reason, fall back to scene root
+                // If there is no current item selected for some reason, fall back to scene root,
+                // except when dealing with multiselection, during which currentIndex can become -1 temporarily.
                 if (entityTreeView.selection.currentIndex.row === -1) {
                     selectedEntityName = ""
-                    if (!selectionList.length) {
-                        editorScene.clearSelectionBoxes()
-                        selectedEntity.showSelectionBox = true
+                    if (!editorScene.multiSelection)
                         selectSceneRoot()
-                    }
                 } else {
                     entityTreeView.sceneRootSelected =
                             (editorScene.sceneModel.sceneEntityIndex() === entityTreeView.selection.currentIndex)
@@ -452,17 +448,13 @@ Item {
                                 selectedEntity.itemType() === EditorSceneItem.Group
                         selectedEntityName = editorScene.sceneModel.entityName(
                                     entityTreeView.selection.currentIndex)
-                        // Don't clear selection boxes if there are items in multiselection list
-                        if (!selectionList.length) {
-                            editorScene.clearSelectionBoxes()
-                            selectedEntity.showSelectionBox = true
-                        }
                     } else {
                         // Should never get here
                         selectedEntityName = ""
-                        editorScene.clearSelectionBoxes()
+                        selectSceneRoot()
                     }
-                    editorScene.selection = selectedEntity.entity()
+                    if (!editorScene.multiSelection)
+                        editorScene.selection = selectedEntity.entity()
                 }
             }
         }
diff --git a/editorlib/qml/GeneralPropertyView.qml b/editorlib/qml/GeneralPropertyView.qml
index 62a470f..d6e0be7 100644
--- a/editorlib/qml/GeneralPropertyView.qml
+++ b/editorlib/qml/GeneralPropertyView.qml
@@ -46,7 +46,7 @@ Item {
     Layout.minimumHeight: componentHeight
     Layout.maximumHeight: Layout.minimumHeight
 
-    visible: !entityTree.multiSelect
+    visible: !editorScene.multiSelection
 
     Component.onCompleted: {
         componentHeight = columnLayout.y + columnLayout.height
diff --git a/editorlib/qml/main.qml b/editorlib/qml/main.qml
index 3d78a8d..85115a4 100644
--- a/editorlib/qml/main.qml
+++ b/editorlib/qml/main.qml
@@ -123,8 +123,6 @@ ApplicationWindow {
 
     property real qlcControlHeight: 28
 
-    property var selectionList: []
-
     property string systemLanguage: editorScene.language
 
     toolBar: EditorToolbar {}
@@ -250,7 +248,7 @@ ApplicationWindow {
         sequence: StandardKey.Copy
         onActivated: {
             // Prevent copying multiselection (for now, at least)
-            if (!selectionList.length)
+            if (!editorScene.multiSelection)
                 mainwindow.copyEntity(selectedEntityName)
         }
     }
@@ -276,7 +274,7 @@ ApplicationWindow {
         sequence: StandardKey.Cut
         onActivated: {
             // Prevent cutting multiselection (for now, at least)
-            if (!selectionList.length)
+            if (!editorScene.multiSelection)
                 mainwindow.cutEntity(selectedEntityName, selectedEntity)
         }
     }
@@ -329,29 +327,11 @@ ApplicationWindow {
         freeView: true
 
         onSelectionChanged: {
-            if (multiSelection.length >= 1) {
-                entityTree.multiSelect = true
-            } else {
-                selectionList.length = 0
-                entityTree.multiSelect = false
-            }
             restoreSelection(selection)
         }
 
-        onMultiSelectionChanged: {
-            selectionList = multiSelection
-            entityTree.multiSelectedCamera = false
-            // Deselect old ones
-            entityTree.view.selection.clear()
-            // Dig indexes of all selected entities and pass the selections to entitytree
-            for (var i = 0; i < multiSelection.length; ++i) {
-                var index = editorScene.sceneModel.getModelIndexByName(multiSelection[i])
-                entityTree.view.selection.select(index, ItemSelectionModel.Select)
-                if (editorScene.sceneModel.editorSceneItemFromIndex(index).itemType()
-                        === EditorSceneItem.Camera) {
-                    entityTree.multiSelectedCamera = true
-                }
-            }
+        onMultiSelectionListChanged: {
+            restoreMultiSelection(editorScene.multiSelectionList)
         }
 
         onErrorChanged: {
@@ -374,18 +354,28 @@ ApplicationWindow {
             selectIndex(index)
         }
 
+        function restoreMultiSelection(selectionList) {
+            // Deselect old ones
+            entityTree.view.selection.clear()
+            // Dig indexes of all selected entities and pass the selections to entitytree
+            for (var i = 0; i < selectionList.length; ++i) {
+                var index = editorScene.sceneModel.getModelIndexByName(multiSelectionList[i])
+                entityTree.view.selection.select(index, ItemSelectionModel.Select)
+                expandTo(index)
+            }
+        }
+
         function selectIndex(index) {
             expandTo(index)
             entityTree.view.forceActiveFocus()
-            if (!entityTree.multiSelect)
-                entityTree.view.selection.setCurrentIndex(index, ItemSelectionModel.ClearAndSelect)
+            entityTree.view.selection.setCurrentIndex(index, ItemSelectionModel.ClearAndSelect)
         }
 
         function expandTo(index) {
             var target = index
             do {
-                target = target.parent
                 entityTree.view.expand(target)
+                target = target.parent
             } while (target.valid)
         }
     }
diff --git a/editorlib/src/editorscene.cpp b/editorlib/src/editorscene.cpp
index 1eb9cdd..d4ca572 100644
--- a/editorlib/src/editorscene.cpp
+++ b/editorlib/src/editorscene.cpp
@@ -120,8 +120,7 @@ EditorScene::EditorScene(QObject *parent)
     , m_gridSize(3)
     , m_duplicateCount(0)
     , m_previousDuplicate(nullptr)
-    , m_multiSelect(false)
-    , m_previousSelectedEntity(nullptr)
+    , m_ctrlDownOnLastLeftPress(false)
     , m_clipboardOperation(ClipboardNone)
 {
     setLanguage(language());
@@ -200,13 +199,6 @@ void EditorScene::addEntity(Qt3DCore::QEntity *entity, int index, Qt3DCore::QEnt
                 addEntity(childEntity);
         }
     }
-
-    if (!m_selectedEntityNameList.isEmpty()) {
-        // Clear multiselection list, otherwise treeview gets messed up
-        m_selectedEntityNameList.clear();
-        m_multiSelect = false;
-        emit multiSelectionChanged(m_selectedEntityNameList);
-    }
 }
 
 // Removed entity is deleted
@@ -243,7 +235,7 @@ void EditorScene::removeEntity(Qt3DCore::QEntity *entity)
 
     m_sceneItems.remove(entity->id());
 
-    if (m_sceneEntity && m_selectedEntity == entity)
+    if (!multiSelection() && m_sceneEntity && m_selectedEntity == entity)
         setSelection(m_sceneEntity);
 
     delete item;
@@ -1744,30 +1736,33 @@ Qt3DRender::QCamera *EditorScene::frameGraphCamera() const
 
 void EditorScene::setSelection(Qt3DCore::QEntity *entity)
 {
+    // Setting selection implies end to multiSelection
+    if (m_selectedEntityNameList.size())
+        clearMultiSelection();
     EditorSceneItem *item = m_sceneItems.value(entity->id(), nullptr);
     if (item) {
         if (entity != m_selectedEntity) {
-            if (m_selectedEntity)
-                connectDragHandles(m_sceneItems.value(m_selectedEntity->id(), nullptr), false);
+            if (m_selectedEntity) {
+                EditorSceneItem *oldItem = m_sceneItems.value(m_selectedEntity->id(), nullptr);
+                if (oldItem) {
+                    connectDragHandles(oldItem, false);
+                    oldItem->setShowSelectionBox(false);
+                }
+            }
 
             m_selectedEntity = entity;
 
             if (m_selectedEntity) {
                 connectDragHandles(item, true);
+                if (m_selectedEntity != m_sceneEntity)
+                    item->setShowSelectionBox(true);
                 m_selectedEntityTransform = EditorUtils::entityTransform(m_selectedEntity);
             }
 
-            if (!m_multiSelect && m_selectedEntity != m_rootEntity)
-                m_previousSelectedEntity = m_selectedEntity;
-            else
-                m_previousSelectedEntity = nullptr;
-
             // Emit signal to highlight the entity from the list
             emit selectionChanged(m_selectedEntity);
-        } else if (!m_multiSelect) {
-            clearSelectionBoxes(m_selectedEntity);
         }
-        m_dragHandlesTransform->setEnabled(item->isSelectionBoxShowing() && !m_multiSelect);
+        m_dragHandlesTransform->setEnabled(item->isSelectionBoxShowing());
 
         if (item->itemType() == EditorSceneItem::Camera) {
             // Disable scale handles for cameras
@@ -1818,47 +1813,29 @@ void EditorScene::setSelection(Qt3DCore::QEntity *entity)
         handleSelectionTransformChange();
     } else {
         m_dragHandlesTransform->setEnabled(false);
+        if (m_selectedEntity != m_sceneEntity)
+            setSelection(m_sceneEntity);
     }
 }
 
-QString EditorScene::previousSelectedEntityName() const {
-    if (m_previousSelectedEntity)
-        return m_previousSelectedEntity->objectName();
-    else
-        return QString();
-}
-
-void EditorScene::setMultiSelection(const QStringList &multiSelection)
-{
-    if (m_selectedEntityNameList != multiSelection) {
-        checkMultiSelectionHighlights(m_selectedEntityNameList, multiSelection);
-        m_selectedEntityNameList = multiSelection;
-    }
-}
-
-QStringList EditorScene::multiSelection()
-{
-    return m_selectedEntityNameList;
-}
-
-void EditorScene::addToMultiSelection(const QString &name)
+void EditorScene::toggleEntityMultiSelection(const QString &name)
 {
-    QStringList oldList = m_selectedEntityNameList;
-    // Add previously selected one, if different than new one and other than scene root.
-    if (m_selectedEntityNameList.isEmpty() && m_pickedEntity != m_selectedEntity
-            && m_selectedEntity != m_sceneEntity) {
-        m_selectedEntityNameList.append(previousSelectedEntityName());
-    }
     // If the new one is already in, remove it. Otherwise add it.
-    if (!m_selectedEntityNameList.contains(name))
-        m_selectedEntityNameList.append(name);
+    if (m_selectedEntityNameList.contains(name))
+        removeEntityFromMultiSelection(name);
     else
-        m_selectedEntityNameList.removeOne(name);
+        addEntityToMultiSelection(name);
+}
 
-    // Emit multiselection list if it changed
-    if (oldList != m_selectedEntityNameList) {
+void EditorScene::clearMultiSelection()
+{
+    if (m_selectedEntityNameList.size() > 0) {
+        QStringList oldList = m_selectedEntityNameList;
+        m_selectedEntityNameList.clear();
         checkMultiSelectionHighlights(oldList, m_selectedEntityNameList);
-        emit multiSelectionChanged(m_selectedEntityNameList);
+        emit multiSelectionChanged(false);
+        emit multiSelectionListChanged();
+        setSelection(m_sceneEntity);
     }
 }
 
@@ -1875,6 +1852,69 @@ QVector3D EditorScene::getMultiSelectionCenter()
     return m_selectedEntityNameList.size() ? (pos / m_selectedEntityNameList.size()) : QVector3D();
 }
 
+void EditorScene::addEntityToMultiSelection(const QString &name)
+{
+    QStringList oldList = m_selectedEntityNameList;
+
+    if (oldList.size() == 0) {
+        // Do not add if multiselecting the currently selected entity as the first entity
+        if (m_selectedEntity->objectName() == name)
+            return;
+
+        if (m_selectedEntity != m_sceneEntity) {
+            m_selectedEntityNameList.append(m_selectedEntity->objectName());
+            m_dragHandlesTransform->setEnabled(false);
+            handleSelectionTransformChange();
+            m_selectedEntity = nullptr;
+        } else {
+            // Just single-select the new entity and return if the other entity was scene entity
+            EditorSceneItem *item = m_sceneModel->getItemByName(name);
+            if (item) {
+                setSelection(item->entity());
+                return;
+            }
+        }
+    }
+    m_selectedEntityNameList.append(name);
+
+    checkMultiSelectionHighlights(oldList, m_selectedEntityNameList);
+
+    if (oldList.size() == 0)
+        emit multiSelectionChanged(true);
+    emit multiSelectionListChanged();
+}
+
+void EditorScene::removeEntityFromMultiSelection(const QString &name)
+{
+    QStringList oldList = m_selectedEntityNameList;
+    bool removed = m_selectedEntityNameList.removeOne(name);
+
+    if (removed) {
+        checkMultiSelectionHighlights(oldList, m_selectedEntityNameList);
+        bool lastRemoved = m_selectedEntityNameList.size() == 1;
+        EditorSceneItem *lastItem = nullptr;
+        if (lastRemoved) {
+            lastItem = m_sceneModel->getItemByName(m_selectedEntityNameList.at(0));
+            m_selectedEntityNameList.clear();
+            emit multiSelectionChanged(false);
+        }
+        emit multiSelectionListChanged();
+        if (lastRemoved) {
+            if (lastItem)
+                setSelection(lastItem->entity());
+            else
+                setSelection(m_sceneEntity);
+        }
+    }
+}
+
+void EditorScene::renameEntityInMultiSelectionList(const QString &oldName, const QString &newName)
+{
+    int index = m_selectedEntityNameList.indexOf(oldName);
+    if (index > 0)
+        m_selectedEntityNameList.replace(index, newName);
+}
+
 void EditorScene::setClipboardOperation(ClipboardOperation operation)
 {
     if (operation != m_clipboardOperation) {
@@ -1981,34 +2021,30 @@ void EditorScene::clearSelectionBoxes(Qt3DCore::QEntity *skipEntity)
 void EditorScene::endSelectionHandling()
 {
     if (m_dragMode == DragNone && m_pickedEntity) {
-        // Multiselection handling
-        if (m_multiSelect)
-            addToMultiSelection(m_pickedEntity->objectName());
-        else
-            m_selectedEntityNameList.clear();
-
-        // Selection handling
-        if (m_multiSelect && m_selectedEntityNameList.isEmpty())
-            setSelection(m_sceneEntity);
-        else
+        if (m_ctrlDownOnLastLeftPress) {
+            // Multiselection handling
+            toggleEntityMultiSelection(m_pickedEntity->objectName());
+        } else {
+            // Single selection handling
             setSelection(m_pickedEntity);
 
-        // Selecting an object also starts drag, if translate handle is enabled
-        Qt3DRender::QCamera *cameraEntity = qobject_cast<Qt3DRender::QCamera *>(m_pickedEntity);
-        bool viewCenterDrag = cameraEntity && m_cameraViewCenterSelected && !m_viewCenterLocked;
-        bool entityDrag = m_dragHandleTranslateTransform->isEnabled()
-                && m_dragHandlesTransform->isEnabled()
-                && (!cameraEntity || !m_cameraViewCenterSelected);
-        if (viewCenterDrag || entityDrag) {
-            m_dragMode = DragTranslate;
-            m_dragEntity = m_pickedEntity;
-            if (cameraEntity) {
-                if (viewCenterDrag)
-                    m_dragInitialTranslationValue = cameraEntity->viewCenter();
-                else
-                    m_dragInitialTranslationValue = cameraEntity->position();
-            } else {
-                m_dragInitialTranslationValue = m_dragHandlesTransform->translation();
+            // Selecting an object also starts drag, if translate handle is enabled
+            Qt3DRender::QCamera *cameraEntity = qobject_cast<Qt3DRender::QCamera *>(m_pickedEntity);
+            bool viewCenterDrag = cameraEntity && m_cameraViewCenterSelected && !m_viewCenterLocked;
+            bool entityDrag = m_dragHandleTranslateTransform->isEnabled()
+                    && m_dragHandlesTransform->isEnabled()
+                    && (!cameraEntity || !m_cameraViewCenterSelected);
+            if (viewCenterDrag || entityDrag) {
+                m_dragMode = DragTranslate;
+                m_dragEntity = m_pickedEntity;
+                if (cameraEntity) {
+                    if (viewCenterDrag)
+                        m_dragInitialTranslationValue = cameraEntity->viewCenter();
+                    else
+                        m_dragInitialTranslationValue = cameraEntity->position();
+                } else {
+                    m_dragInitialTranslationValue = m_dragHandlesTransform->translation();
+                }
             }
         }
         m_pickedEntity = nullptr;
@@ -2021,6 +2057,14 @@ void EditorScene::handleSelectionTransformChange()
     EditorSceneItem *item = nullptr;
     if (m_selectedEntity && m_selectedEntity != m_sceneEntity)
         item = m_sceneItems.value(m_selectedEntity->id(), nullptr);
+    QPoint translatePoint;
+    QPoint centerPoint;
+    QVector3D translateHandlePos;
+    QVector3D itemCenterHandlePos;
+    QVector3D rotateHandlePos;
+    QVector3D cornerHandlePositions[dragCornerHandleCount];
+    bool showCenterHandle = false;
+
     if (item) {
         Qt3DRender::QCamera *camera = frameGraphCamera();
         resizeCameraViewCenterEntity();
@@ -2041,12 +2085,11 @@ void EditorScene::handleSelectionTransformChange()
 
         // Find out x/y viewport positions of drag handles
 
-        QVector3D translateHandlePos = EditorUtils::projectRay(
+        translateHandlePos = EditorUtils::projectRay(
                     camera->viewMatrix(), camera->projectionMatrix(),
                     m_viewport->width(), m_viewport->height(),
                     m_dragHandlesTransform->matrix() * QVector3D());
 
-        QVector3D cornerHandlePositions[dragCornerHandleCount];
         for (int i = 0; i < dragCornerHandleCount; i++) {
             m_dragHandleScaleTransforms.at(i)->setTranslation(
                         translation * m_dragHandleCornerAdjustments.at(i));
@@ -2060,7 +2103,6 @@ void EditorScene::handleSelectionTransformChange()
 
         // Try to position rotate handle to the upper right corner of the selection box, as
         // drawn on the screen. However, we don't change the corner during drag-rotation.
-        QVector3D rotateHandlePos;
         const float handleDistance = 12.0f;
         if (m_dragMode != DragRotate) {
             float maxDelta = 0.0f;
@@ -2105,11 +2147,7 @@ void EditorScene::handleSelectionTransformChange()
             rotateHandlePos += adjustVector;
         }
 
-        QPoint translatePoint(translateHandlePos.x(), translateHandlePos.y());
-
-        QPoint centerPoint;
-        QVector3D itemCenterHandlePos;
-        bool showCenterHandle = false;
+        translatePoint = QPoint(translateHandlePos.x(), translateHandlePos.y());
         if (item->itemType() != EditorSceneItem::Camera
                 && item->itemType() != EditorSceneItem::Light) {
             itemCenterHandlePos = EditorUtils::projectRay(
@@ -2117,11 +2155,9 @@ void EditorScene::handleSelectionTransformChange()
                         m_viewport->width(), m_viewport->height(),
                         m_dragHandlesTransform->matrix() * m_dragHandleTranslateTransform->matrix()
                         * QVector3D());
-
             centerPoint = QPoint(itemCenterHandlePos.x(), itemCenterHandlePos.y());
             showCenterHandle = translatePoint != centerPoint;
         }
-
         m_meshCenterIndicatorLine->setEnabled(showCenterHandle);
         if (showCenterHandle) {
             QQuaternion rot = QQuaternion::rotationTo(QVector3D(0.0f, 0.0f, 1.0f),
@@ -2132,34 +2168,33 @@ void EditorScene::handleSelectionTransformChange()
                         m_dragHandlesTransform->translation());
             m_meshCenterIndicatorLineTransform->setScale(meshCenter.length());
         }
-
-        // Signal UI to reposition drag handles
-        emit beginDragHandlesRepositioning();
-        emit repositionDragHandle(DragTranslate, translatePoint,
-                                  m_dragHandlesTransform->isEnabled()
-                                  ? m_dragHandleTranslateTransform->isEnabled()
-                                    && translateHandlePos.z() > 0.0f : false, 0,
-                                  translateHandlePos.z());
-        emit repositionDragHandle(DragTranslate, centerPoint,
-                                  m_dragHandlesTransform->isEnabled()
-                                  ? m_dragHandleTranslateTransform->isEnabled()
-                                    && itemCenterHandlePos.z() > 0.0f && showCenterHandle : false,
-                                  1, itemCenterHandlePos.z());
-        emit repositionDragHandle(DragRotate, QPoint(rotateHandlePos.x(), rotateHandlePos.y()),
+    }
+    // Signal UI to reposition drag handles
+    emit beginDragHandlesRepositioning();
+    emit repositionDragHandle(DragTranslate, translatePoint,
+                              m_dragHandlesTransform->isEnabled()
+                              ? m_dragHandleTranslateTransform->isEnabled()
+                                && translateHandlePos.z() > 0.0f : false, 0,
+                              translateHandlePos.z());
+    emit repositionDragHandle(DragTranslate, centerPoint,
+                              m_dragHandlesTransform->isEnabled()
+                              ? m_dragHandleTranslateTransform->isEnabled()
+                                && itemCenterHandlePos.z() > 0.0f && showCenterHandle : false,
+                              1, itemCenterHandlePos.z());
+    emit repositionDragHandle(DragRotate, QPoint(rotateHandlePos.x(), rotateHandlePos.y()),
+                              m_dragHandlesTransform->isEnabled()
+                              ? m_dragHandleRotateTransform->isEnabled()
+                                && rotateHandlePos.z() > 0.0f : false, 0, rotateHandlePos.z());
+    for (int i = 0; i < dragCornerHandleCount; i++) {
+        emit repositionDragHandle(DragScale,
+                                  QPoint(cornerHandlePositions[i].x(),
+                                         cornerHandlePositions[i].y()),
                                   m_dragHandlesTransform->isEnabled()
-                                  ? m_dragHandleRotateTransform->isEnabled()
-                                    && rotateHandlePos.z() > 0.0f : false, 0, rotateHandlePos.z());
-        for (int i = 0; i < dragCornerHandleCount; i++) {
-            emit repositionDragHandle(DragScale,
-                                      QPoint(cornerHandlePositions[i].x(),
-                                             cornerHandlePositions[i].y()),
-                                      m_dragHandlesTransform->isEnabled()
-                                      ? m_dragHandleScaleTransforms.at(0)->isEnabled()
-                                        && cornerHandlePositions[i].z() > 0.0f : false, i,
-                                      cornerHandlePositions[i].z());
-        }
-        emit endDragHandlesRepositioning();
+                                  ? m_dragHandleScaleTransforms.at(0)->isEnabled()
+                                    && cornerHandlePositions[i].z() > 0.0f : false, i,
+                                  cornerHandlePositions[i].z());
     }
+    emit endDragHandlesRepositioning();
 }
 
 void EditorScene::handlePickerPress(Qt3DRender::QPickEvent *event)
@@ -2235,12 +2270,8 @@ bool EditorScene::handleMousePress(QMouseEvent *event)
 {
     m_previousMousePosition = event->pos();
     m_mouseButton = event->button();
-    if (m_mouseButton == Qt::LeftButton) {
-        m_multiSelect = event->modifiers() & Qt::ControlModifier;
-        // Clear multiselection list if m_multiSelect is false
-        if (!m_multiSelect)
-            m_selectedEntityNameList.clear();
-    }
+    if (m_mouseButton == Qt::LeftButton)
+        m_ctrlDownOnLastLeftPress = event->modifiers() & Qt::ControlModifier;
     cancelDrag();
     return false; // Never consume press event
 }
diff --git a/editorlib/src/editorscene.h b/editorlib/src/editorscene.h
index b525c49..c1c0aa0 100644
--- a/editorlib/src/editorscene.h
+++ b/editorlib/src/editorscene.h
@@ -72,7 +72,8 @@ class EditorScene : public QObject
     Q_OBJECT
     Q_PROPERTY(EditorSceneItemModel *sceneModel READ sceneModel CONSTANT)
     Q_PROPERTY(Qt3DCore::QEntity *selection READ selection WRITE setSelection NOTIFY selectionChanged)
-    Q_PROPERTY(QStringList multiSelection READ multiSelection WRITE setMultiSelection NOTIFY multiSelectionChanged)
+    Q_PROPERTY(QStringList multiSelectionList READ multiSelectionList NOTIFY multiSelectionListChanged)
+    Q_PROPERTY(bool multiSelection READ multiSelection NOTIFY multiSelectionChanged)
     Q_PROPERTY(QString error READ error NOTIFY errorChanged)
     Q_PROPERTY(int activeSceneCameraIndex READ activeSceneCameraIndex WRITE setActiveSceneCameraIndex NOTIFY activeSceneCameraIndexChanged)
     Q_PROPERTY(EditorViewportItem *viewport READ viewport WRITE setViewport NOTIFY viewportChanged)
@@ -236,10 +237,14 @@ public:
     Q_INVOKABLE void dragHandleMove(const QPoint &pos, bool shiftDown, bool ctrlDown, bool altDown);
     Q_INVOKABLE void dragHandleRelease();
     Q_INVOKABLE QString sceneRootName() const { return m_sceneEntity->objectName(); }
-    Q_INVOKABLE QString previousSelectedEntityName() const;
-    Q_INVOKABLE void addToMultiSelection(const QString &name);
+    Q_INVOKABLE void toggleEntityMultiSelection(const QString &name);
+    Q_INVOKABLE void clearMultiSelection();
     Q_INVOKABLE QVector3D getMultiSelectionCenter();
 
+    void removeEntityFromMultiSelection(const QString &name);
+    void addEntityToMultiSelection(const QString &name);
+    void renameEntityInMultiSelectionList(const QString &oldName, const QString &newName);
+
     ClipboardOperation clipboardOperation() { return m_clipboardOperation; }
     void setClipboardOperation(ClipboardOperation operation);
 
@@ -256,8 +261,9 @@ public:
     void setSelection(Qt3DCore::QEntity *entity);
     Qt3DCore::QEntity *selection() const { return m_selectedEntity; }
 
-    void setMultiSelection(const QStringList &multiSelection);
-    QStringList multiSelection();
+    QStringList multiSelectionList() { return m_selectedEntityNameList; }
+
+    bool multiSelection() const { return m_selectedEntityNameList.size() > 0; }
 
     const QString &error() const { return m_errorString; }
 
@@ -307,7 +313,8 @@ public slots:
 
 signals:
     void selectionChanged(Qt3DCore::QEntity *selection);
-    void multiSelectionChanged(QStringList multiSelection);
+    void multiSelectionListChanged();
+    void multiSelectionChanged(bool multiSelection);
     void errorChanged(const QString &error);
     void freeViewChanged(bool enabled);
     void activeSceneCameraIndexChanged(int index);
@@ -456,10 +463,9 @@ private:
     int m_gridSize;
     int m_duplicateCount;
     Qt3DCore::QEntity *m_previousDuplicate;
-    bool m_multiSelect;
+    bool m_ctrlDownOnLastLeftPress;
     QStringList m_selectedEntityNameList;
     Qt::MouseButton m_mouseButton;
-    Qt3DCore::QEntity *m_previousSelectedEntity;
     QString m_clipboardEntityName;
     ClipboardOperation m_clipboardOperation;
 
diff --git a/editorlib/src/editorsceneitemmodel.cpp b/editorlib/src/editorsceneitemmodel.cpp
index b1cb8dd..5956c44 100644
--- a/editorlib/src/editorsceneitemmodel.cpp
+++ b/editorlib/src/editorsceneitemmodel.cpp
@@ -260,13 +260,13 @@ QHash<int, QByteArray> EditorSceneItemModel::roleNames() const
 
 void EditorSceneItemModel::resetModel()
 {
-    beginResetModel();
+    QAbstractItemModel::beginResetModel();
 
     // Reconnect all entities
     disconnectEntity(m_scene->sceneEntityItem()->entity());
     connectEntity(m_scene->sceneEntityItem()->entity());
 
-    endResetModel();
+    QAbstractItemModel::endResetModel();
 
     // Restore TreeView branch expansions, since resetting the model will collapse the branches
     QModelIndexList expandedIndexList;
@@ -274,8 +274,9 @@ void EditorSceneItemModel::resetModel()
         expandedIndexList.append(getModelIndexByName(entityName));
     emit expandItems(expandedIndexList);
 
-    // Select scene root after reset
-    emit selectIndex(sceneEntityIndex());
+    // Select scene root after reset, unless multiselecting
+    if (!m_scene->multiSelection())
+        emit selectIndex(sceneEntityIndex());
 }
 
 EditorSceneItem *EditorSceneItemModel::editorSceneItemFromIndex(const QModelIndex &index) const
@@ -464,11 +465,7 @@ const QString EditorSceneItemModel::setEntityName(const QModelIndex &index, cons
 
     setData(index, finalName, NameRole);
 
-    QStringList multiSelection = m_scene->multiSelection();
-    if (multiSelection.removeOne(oldName)) {
-        multiSelection.append(finalName);
-        m_scene->setMultiSelection(multiSelection);
-    }
+    m_scene->renameEntityInMultiSelectionList(oldName, finalName);
 
     if (oldName == m_scene->clipboardContent())
         m_scene->setClipboardContent(name);
@@ -537,11 +534,13 @@ bool EditorSceneItemModel::canReparent(EditorSceneItem *newParentItem,
                                        EditorSceneItem *movedItem, bool allowSameParent)
 {
     // Dropping into camera is invalid.
+    // Reparenting camera is invalid.
     // Dropping into same parent is invalid.
     // Dropping item into its descendant is invalid.
     // If allowSameParent is true, "reparenting" under the same parent is allowed. This is useful
     // for entity tree copy & paste functionality.
-    bool reparentOk = !EditorUtils::entityCameraLens(newParentItem->entity())
+    bool reparentOk = newParentItem->itemType() != EditorSceneItem::Camera
+            && movedItem->itemType() != EditorSceneItem::Camera
             && movedItem != newParentItem
             && !EditorUtils::isDescendant(movedItem, newParentItem);
     if (!allowSameParent)
diff --git a/editorlib/src/undohandler/resetentitycommand.cpp b/editorlib/src/undohandler/resetentitycommand.cpp
index e581488..536f15e 100644
--- a/editorlib/src/undohandler/resetentitycommand.cpp
+++ b/editorlib/src/undohandler/resetentitycommand.cpp
@@ -62,11 +62,6 @@ void ResetEntityCommand::undo()
         m_sceneModel->insertExistingEntity(m_removedEntity, m_row, parentIndex);
         m_removedEntity = nullptr;
 
-        if (m_type == EditorUtils::InsertableEntities::LightEntity
-                || m_type == EditorUtils::InsertableEntities::CameraEntity) {
-            m_sceneModel->resetModel();
-        }
-
         emit m_sceneModel->selectIndex(m_sceneModel->getModelIndexByName(m_entityName));
     }
 }
diff --git a/editorlib/src/undohandler/undohandler.cpp b/editorlib/src/undohandler/undohandler.cpp
index 59adf79..9d6a270 100644
--- a/editorlib/src/undohandler/undohandler.cpp
+++ b/editorlib/src/undohandler/undohandler.cpp
@@ -42,6 +42,7 @@
 #include "importentitycommand.h"
 #include "resetentitycommand.h"
 #include "resettransformcommand.h"
+#include "editorsceneitem.h"
 
 #include <QtWidgets/QUndoStack>
 
@@ -235,7 +236,14 @@ void UndoHandler::createReparentEntityCommand(const QString &newParentName,
     if (newParentName.isEmpty() || entityName.isEmpty())
         return;
 
-    m_undoStack->push(new ReparentEntityCommand(m_scene->sceneModel(), newParentName, entityName));
+    // Don't create commands for illegal reparentings
+    EditorSceneItem *newParentItem = m_scene->sceneModel()->getItemByName(newParentName);
+    EditorSceneItem *entityItem = m_scene->sceneModel()->getItemByName(entityName);
+
+    if (m_scene->sceneModel()->canReparent(newParentItem, entityItem)) {
+        m_undoStack->push(new ReparentEntityCommand(m_scene->sceneModel(), newParentName,
+                                                    entityName));
+    }
 }
 
 void UndoHandler::createImportEntityCommand(const QUrl &url)