implement history panel

app/core.cpp

@@ -29,6 +29,7 @@
 #include <QInputDialog>
 #include <QMessageBox>
 #include <QStyleFactory>
+#include "window/mainwindow/mainwindowundo.h"
 #ifdef Q_OS_WINDOWS
 #include <QtPlatformHeaders/QWindowsWindowFunctions>
 #endif
@@ -450,14 +451,13 @@ void Core::CreateNewSequence()
     command->add_child(new NodeAddCommand(active_project, new_sequence));
     command->add_child(new FolderAddChild(GetSelectedFolderInActiveProject(), new_sequence));
     command->add_child(new NodeSetPositionCommand(new_sequence, new_sequence, Node::Position()));
+    command->add_child(new OpenSequenceCommand(new_sequence));
 
     // Create and connect default nodes to new sequence
     new_sequence->add_default_nodes(command);
 
     Core::instance()->undo_stack()->push(command);
 
-    Core::instance()->main_window()->OpenSequence(new_sequence);
-
   } else {
 
     // If the dialog was accepted, ownership goes to the AddItemCommand. But if we get here, just delete
@@ -575,7 +575,7 @@ void Core::ImportTaskComplete(Task* task)
     d.exec();
   }
 
-  undo_stack_.pushIfHasChildren(command);
+  undo_stack_.push(command);
 
   main_window_->SelectFootage(import_task->GetImportedFootage());
 }

app/dialog/configbase/configdialogbase.cpp

@@ -73,7 +73,7 @@ void ConfigDialogBase::accept()
     tab->Accept(command);
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 
   AcceptEvent();
 

app/dialog/footageproperties/footageproperties.cpp

@@ -192,7 +192,7 @@ void FootagePropertiesDialog::accept()
     static_cast<StreamProperties*>(stacked_widget_->widget(i))->Accept(command);
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 
   QDialog::accept();
 }

app/dialog/keyframeproperties/keyframeproperties.cpp

@@ -219,7 +219,7 @@ void KeyframePropertiesDialog::accept()
     }
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 
   QDialog::accept();
 }

app/dialog/markerproperties/markerpropertiesdialog.cpp

@@ -147,7 +147,7 @@ void MarkerPropertiesDialog::accept()
     command->add_child(new MarkerChangeTimeCommand(markers_.front(), TimeRange(in_slider_->GetValue(), out_slider_->GetValue())));
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 
   super::accept();
 }

app/node/gizmo/text.cpp

@@ -43,7 +43,7 @@ void TextGizmo::UpdateInputHtml(const QString &s, const rational &time)
   if (input_.IsValid()) {
     MultiUndoCommand *command = new MultiUndoCommand();
     Node::SetValueAtTime(input_.input(), time, s, input_.track(), command, true);
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
   }
 }
 

app/panel/CMakeLists.txt

@@ -17,6 +17,7 @@
 add_subdirectory(audiomonitor)
 add_subdirectory(curve)
 add_subdirectory(footageviewer)
+add_subdirectory(history)
 add_subdirectory(multicam)
 add_subdirectory(node)
 add_subdirectory(param)

app/panel/history/CMakeLists.txt

@@ -0,0 +1,22 @@
+# Olive - Non-Linear Video Editor
+# Copyright (C) 2023 Olive Studios LLC
+#
+# 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 3 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, see <http://www.gnu.org/licenses/>.
+
+set(OLIVE_SOURCES
+  ${OLIVE_SOURCES}
+  panel/history/historypanel.h
+  panel/history/historypanel.cpp
+  PARENT_SCOPE
+)

app/panel/history/historypanel.cpp

@@ -0,0 +1,40 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+
+  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 3 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, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "historypanel.h"
+
+#include "widget/history/historywidget.h"
+
+namespace olive {
+
+HistoryPanel::HistoryPanel() :
+  PanelWidget(QStringLiteral("HistoryPanel"))
+{
+  SetWidgetWithPadding(new HistoryWidget(this));
+
+  Retranslate();
+}
+
+void HistoryPanel::Retranslate()
+{
+  SetTitle(tr("History"));
+}
+
+}

app/panel/history/historypanel.h

@@ -0,0 +1,41 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+
+  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 3 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, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef HISTORYPANEL_H
+#define HISTORYPANEL_H
+
+#include "panel/panel.h"
+
+namespace olive {
+
+class HistoryPanel : public PanelWidget
+{
+  Q_OBJECT
+public:
+  HistoryPanel();
+
+protected:
+  virtual void Retranslate() override;
+
+};
+
+}
+
+#endif // HISTORYPANEL_H

app/undo/undostack.cpp

@@ -26,6 +26,19 @@ namespace olive {
 
 const int UndoStack::kMaxUndoCommands = 200;
 
+class EmptyCommand : public UndoCommand
+{
+public:
+  EmptyCommand(){}
+
+  virtual Project* GetRelevantProject() const override {return nullptr;}
+
+protected:
+  virtual void redo() override {}
+  virtual void undo() override {}
+
+};
+
 UndoStack::UndoStack()
 {
   undo_action_ = new QAction();
@@ -34,6 +47,7 @@ UndoStack::UndoStack()
   redo_action_ = new QAction();
   connect(redo_action_, &QAction::triggered, this, &UndoStack::redo);
 
+  clear();
   UpdateActions();
 }
 
@@ -45,35 +59,51 @@ UndoStack::~UndoStack()
   delete redo_action_;
 }
 
-void UndoStack::pushIfHasChildren(MultiUndoCommand *command)
-{
-  if (command->child_count() > 0) {
-    push(command);
-  } else {
-    delete command;
-  }
-}
-
 void UndoStack::push(UndoCommand *command)
 {
-  command->redo_and_set_modified();
-  commands_.push_back(command);
-
-  if (commands_.size() > kMaxUndoCommands) {
-    delete commands_.front();
-    commands_.pop_front();
+  MultiUndoCommand *mcu = dynamic_cast<MultiUndoCommand*>(command);
+  if (mcu && mcu->child_count() == 0) {
+    delete command;
+    return;
   }
 
+  // Clear any redoable commands
+  this->beginRemoveRows(QModelIndex(), commands_.size(), commands_.size() + undone_commands_.size());
   if (CanRedo()) {
     for (auto it=undone_commands_.cbegin(); it!=undone_commands_.cend(); it++) {
       delete (*it);
     }
     undone_commands_.clear();
   }
+  this->endRemoveRows();
+
+  // Do command and push
+  this->beginInsertRows(QModelIndex(), commands_.size(), commands_.size());
+  command->redo_and_set_modified();
+  commands_.push_back(command);
+  this->endInsertRows();
+
+  // Delete oldest
+  if (commands_.size() > kMaxUndoCommands) {
+    this->beginRemoveRows(QModelIndex(), 0, 0);
+    delete commands_.front();
+    commands_.pop_front();
+    this->endRemoveRows();
+  }
 
   UpdateActions();
 }
 
+void UndoStack::jump(size_t index)
+{
+  while (commands_.size() > index) {
+    undo();
+  }
+  while (commands_.size() < index) {
+    redo();
+  }
+}
+
 void UndoStack::undo()
 {
   if (CanUndo()) {
@@ -110,10 +140,27 @@ void UndoStack::redo()
 
 void UndoStack::clear()
 {
+  this->beginResetModel();
+
   for (auto it=commands_.cbegin(); it!=commands_.cend(); it++) {
     delete (*it);
   }
   commands_.clear();
+  for (auto it=undone_commands_.cbegin(); it!=undone_commands_.cend(); it++) {
+    delete (*it);
+  }
+  undone_commands_.clear();
+
+  this->endResetModel();
+
+  EmptyCommand *e = new EmptyCommand();
+  e->set_name(tr("New/Open Project"));
+  push(e);
+}
+
+bool UndoStack::CanUndo() const
+{
+  return !commands_.empty() && !dynamic_cast<EmptyCommand*>(commands_.back());
 }
 
 void UndoStack::UpdateActions()
@@ -123,6 +170,86 @@ void UndoStack::UpdateActions()
 
   undo_action_->setText(QCoreApplication::translate("UndoStack", "Undo %1").arg(CanUndo() ? commands_.back()->name() : QString()));
   redo_action_->setText(QCoreApplication::translate("UndoStack", "Redo %1").arg(CanRedo() ? undone_commands_.front()->name() : QString()));
+
+  emit indexChanged(commands_.size());
+}
+
+int UndoStack::columnCount(const QModelIndex &parent) const
+{
+  if (parent.isValid()) {
+    return 0;
+  }
+  return 2;
+}
+
+QVariant UndoStack::data(const QModelIndex &index, int role) const
+{
+  if (role == Qt::DisplayRole) {
+    switch (index.column()) {
+    case 0:
+      return index.row() + 1;
+    case 1:
+    {
+      std::list<UndoCommand*>::const_iterator it;
+      size_t real_index = index.row();
+      if (real_index < commands_.size()) {
+        it = commands_.cbegin();
+      } else {
+        real_index -= commands_.size();
+        it = undone_commands_.cbegin();
+      }
+      for (size_t i = 0; i < real_index; i++) {
+        it++;
+      }
+      const QString &name = (*it)->name();
+      return (name.isEmpty()) ? QStringLiteral("Command") : name;
+    }
+    }
+  } else if (role == Qt::ForegroundRole) {
+    if (size_t(index.row()) >= commands_.size()) {
+      return QVariant(QColor(Qt::gray));
+    }
+  }
+
+  return QVariant();
+}
+
+QModelIndex UndoStack::index(int row, int column, const QModelIndex &parent) const
+{
+  return createIndex(row, column, nullptr);
+}
+
+QModelIndex UndoStack::parent(const QModelIndex &index) const
+{
+  return QModelIndex();
+}
+
+int UndoStack::rowCount(const QModelIndex &parent) const
+{
+  if (parent.isValid()) {
+    return 0;
+  }
+
+  return commands_.size() + undone_commands_.size();
+}
+
+QVariant UndoStack::headerData(int section, Qt::Orientation orientation, int role) const
+{
+  if (role == Qt::DisplayRole) {
+    switch (section) {
+    case 0:
+      return QStringLiteral("Number");
+    case 1:
+      return QStringLiteral("Action");
+    }
+  }
+
+  return QVariant();
+}
+
+bool UndoStack::hasChildren(const QModelIndex &parent) const
+{
+  return !parent.isValid();
 }
 
 }

app/undo/undostack.h

@@ -22,13 +22,14 @@
 #define UNDOSTACK_H
 
 #include <QAction>
+#include <QAbstractItemModel>
 
 #include "common/define.h"
 #include "undo/undocommand.h"
 
 namespace olive {
 
-class UndoStack : public QObject
+class UndoStack : public QAbstractItemModel
 {
   Q_OBJECT
 public:
@@ -36,21 +37,13 @@ public:
 
   virtual ~UndoStack() override;
 
-  /**
-   * @brief A wrapper for push() that either pushes if the command has children or deletes if not
-   *
-   * This function takes ownership of `command`, and may delete it so it should never be accessed after this call.
-   */
-  void pushIfHasChildren(MultiUndoCommand* command);
-
   void push(UndoCommand* command);
 
+  void jump(size_t index);
+
   void clear();
 
-  bool CanUndo() const
-  {
-    return !commands_.empty();
-  }
+  bool CanUndo() const;
 
   bool CanRedo() const
   {
@@ -69,6 +62,17 @@ public:
     return redo_action_;
   }
 
+  virtual int columnCount(const QModelIndex &parent = QModelIndex()) const override;
+  virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+  virtual QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override;
+  virtual QModelIndex parent(const QModelIndex &index) const override;
+  virtual int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+  virtual QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;
+  virtual bool hasChildren(const QModelIndex &parent = QModelIndex()) const override;
+
+signals:
+  void indexChanged(int i);
+
 public slots:
   void undo();
 

app/widget/CMakeLists.txt

@@ -27,6 +27,7 @@ add_subdirectory(filefield)
 add_subdirectory(flowlayout)
 add_subdirectory(focusablelineedit)
 add_subdirectory(handmovableview)
+add_subdirectory(history)
 add_subdirectory(keyframeview)
 add_subdirectory(manageddisplay)
 add_subdirectory(menu)

app/widget/history/CMakeLists.txt

@@ -0,0 +1,22 @@
+# Olive - Non-Linear Video Editor
+# Copyright (C) 2023 Olive Studios LLC
+#
+# 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 3 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, see <http://www.gnu.org/licenses/>.
+
+set(OLIVE_SOURCES
+  ${OLIVE_SOURCES}
+  widget/history/historywidget.cpp
+  widget/history/historywidget.h
+  PARENT_SCOPE
+)

app/widget/history/historywidget.cpp

@@ -0,0 +1,49 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+
+  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 3 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, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "historywidget.h"
+
+#include "core.h"
+
+namespace olive {
+
+HistoryWidget::HistoryWidget(QWidget *parent) :
+  QTreeView(parent)
+{
+  stack_ = Core::instance()->undo_stack();
+
+  this->setModel(stack_);
+  this->setRootIsDecorated(false);
+  connect(stack_, &UndoStack::indexChanged, this, &HistoryWidget::indexChanged);
+  connect(this->selectionModel(), &QItemSelectionModel::currentRowChanged, this, &HistoryWidget::currentRowChanged);
+}
+
+void HistoryWidget::indexChanged(int i)
+{
+  this->selectionModel()->select(this->model()->index(i-1, 0), QItemSelectionModel::ClearAndSelect | QItemSelectionModel::Rows);
+}
+
+void HistoryWidget::currentRowChanged(const QModelIndex &current, const QModelIndex &previous)
+{
+  size_t jump_to = (current.row() + 1);
+  stack_->jump(jump_to);
+}
+
+}

app/widget/history/historywidget.h

@@ -0,0 +1,50 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+
+  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 3 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, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef HISTORYWIDGET_H
+#define HISTORYWIDGET_H
+
+#include <QTreeView>
+
+#include "undo/undostack.h"
+
+namespace olive {
+
+class HistoryWidget : public QTreeView
+{
+  Q_OBJECT
+public:
+  HistoryWidget(QWidget *parent = nullptr);
+
+private:
+  UndoStack *stack_;
+
+  size_t current_row_;
+
+private slots:
+  void indexChanged(int i);
+
+  void currentRowChanged(const QModelIndex &current, const QModelIndex &previous);
+
+};
+
+}
+
+#endif // HISTORYWIDGET_H

app/widget/keyframeview/keyframeview.cpp

@@ -61,7 +61,7 @@ void KeyframeView::DeleteSelected()
       command->add_child(new NodeParamRemoveKeyframeCommand(key));
     }
 
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
   }
 }
 
@@ -247,7 +247,7 @@ bool KeyframeView::Paste(std::function<Node *(const QString &)> find_node_functi
       }
     }
 
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
     return true;
   }
 

app/widget/nodeparamview/nodeparamview.cpp

@@ -646,7 +646,7 @@ bool NodeParamView::Paste(QWidget *parent, std::function<QHash<Node *, Node*>(co
     }
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 
   return true;
 }

app/widget/nodeparamview/nodeparamviewcontext.cpp

@@ -180,7 +180,7 @@ void NodeParamViewContext::AddEffectMenuItemTriggered(QAction *a)
       command->add_child(new NodeEdgeAddCommand(n, ctx_input));
     }
 
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
   }
 }
 

app/widget/nodeparamview/nodeparamviewkeyframecontrol.cpp

@@ -176,7 +176,7 @@ void NodeParamViewKeyframeControl::ToggleKeyframe(bool e)
     }
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 void NodeParamViewKeyframeControl::UpdateState()
@@ -276,7 +276,7 @@ void NodeParamViewKeyframeControl::KeyframeEnableBtnClicked(bool e)
     }
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 void NodeParamViewKeyframeControl::KeyframeEnableChanged(const NodeInput &input, bool e)

app/widget/nodeparamview/nodeparamviewwidgetbridge.cpp

@@ -190,7 +190,7 @@ void NodeParamViewWidgetBridge::SetInputValue(const QVariant &value, int track)
 
   SetInputValueInternal(value, track, command, true);
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 void NodeParamViewWidgetBridge::SetInputValueInternal(const QVariant &value, int track, MultiUndoCommand *command, bool insert_on_all_tracks_if_no_key)
@@ -314,7 +314,7 @@ void NodeParamViewWidgetBridge::WidgetCallback()
     n->SetInputProperty(GetInnerInput().input(), QStringLiteral("col_look"), c.color_output().look());
     n->blockSignals(false);
 
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
     break;
   }
   case NodeValue::kText:

app/widget/nodeview/nodeview.cpp

@@ -411,7 +411,7 @@ void NodeView::keyPressEvent(QKeyEvent *event)
         }
       }
     }
-    Core::instance()->undo_stack()->pushIfHasChildren(pos_command);
+    Core::instance()->undo_stack()->push(pos_command);
     break;
   }
   case Qt::Key_Escape:
@@ -581,7 +581,7 @@ void NodeView::mouseReleaseEvent(QMouseEvent *event)
   }
   dragging_items_.clear();
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 
   if (!had_attached_items) {
     super::mouseReleaseEvent(event);
@@ -674,7 +674,7 @@ void NodeView::dropEvent(QDropEvent *event)
   if (Node *drop_ctx = GetContextAtMousePos(event->pos())) {
     MultiUndoCommand *command = new MultiUndoCommand();
     QVector<Node*> select_nodes = ProcessDroppingAttachedNodes(command, drop_ctx, event->pos());
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
 
     DeselectAll();
     scene_.context_map().value(drop_ctx)->Select(select_nodes);
@@ -1680,7 +1680,7 @@ void NodeView::EndEdgeDrag(bool cancel)
   }
   create_edge_expanded_items_.clear();
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 void NodeView::PostPaste(const QVector<Node *> &new_nodes, const Node::PositionMap &map)

app/widget/projectexplorer/projectexplorer.cpp

@@ -666,7 +666,7 @@ void ProjectExplorer::DeleteSelected()
   bool check_if_item_is_in_use = true;
 
   if (DeleteItemsInternal(selected, check_if_item_is_in_use, command)) {
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
   } else {
     delete command;
   }

app/widget/projectexplorer/projectviewmodel.cpp

@@ -374,7 +374,7 @@ bool ProjectViewModel::dropMimeData(const QMimeData *data, Qt::DropAction action
       }
     }
 
-    Core::instance()->undo_stack()->pushIfHasChildren(move_command);
+    Core::instance()->undo_stack()->push(move_command);
 
     return true;
 

app/widget/timelinewidget/timelinewidget.cpp

@@ -545,7 +545,7 @@ void TimelineWidget::DeleteSelected(bool ripple)
     command->add_child(ripple_command);
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 
   // Ensures any current drag operations are cancelled
   ClearGhosts();
@@ -773,7 +773,7 @@ void TimelineWidget::ToggleSelectedEnabled()
                                                      !i->is_enabled()));
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 void TimelineWidget::SetColorLabel(int index)
@@ -845,7 +845,7 @@ void TimelineWidget::RecordingCallback(const QString &filename, const TimeRange
     import_command->add_child(subimport_command);
 
     import_tool_->PlaceAt({task.GetImportedFootage().front()}, time.in(), false, import_command, track.index());
-    Core::instance()->undo_stack()->pushIfHasChildren(import_command);
+    Core::instance()->undo_stack()->push(import_command);
   }
 }
 
@@ -1452,7 +1452,7 @@ void TimelineWidget::RenameSelectedBlocks()
   }
 
   Core::instance()->LabelNodes(nodes);
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 void TimelineWidget::TrackAboutToBeDeleted(Track *track)
@@ -1475,7 +1475,7 @@ void TimelineWidget::SetSelectedClipsAutocaching(bool e)
     }
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 void TimelineWidget::CacheClips()
@@ -1574,7 +1574,7 @@ void TimelineWidget::MulticamEnabledTriggered(bool e)
     }
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 void TimelineWidget::ForceUpdateRubberBand()
@@ -1918,7 +1918,7 @@ void TimelineWidget::EditTo(Timeline::MovementMode mode)
     }
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 void TimelineWidget::UpdateViewports(const Track::Type &type)
@@ -1953,8 +1953,6 @@ bool TimelineWidget::PasteInternal(bool insert)
     }
   }
 
-  qDebug() << "pasing" << res.GetLoadData().nodes.size() << "nodes";
-
   for (auto it = res.GetLoadData().promised_connections.cbegin(); it != res.GetLoadData().promised_connections.cend(); it++) {
     auto oc = *it;
     command->add_child(new NodeEdgeAddCommand(oc.first, oc.second));
@@ -1988,7 +1986,7 @@ bool TimelineWidget::PasteInternal(bool insert)
                                                   paste_start + in));
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 
   return true;
 }

app/widget/timelinewidget/tool/import.cpp

@@ -184,7 +184,7 @@ void ImportTool::DragDrop(TimelineViewMouseEvent *event)
   if (!dragged_footage_.isEmpty()) {
     auto command = new MultiUndoCommand();
     DropGhosts(event->GetModifiers() & Qt::ControlModifier, command);
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
 
     event->accept();
   } else {

app/widget/timelinewidget/tool/pointer.cpp

@@ -815,7 +815,7 @@ void PointerTool::FinishDrag(TimelineViewMouseEvent *event)
     }
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 Timeline::MovementMode PointerTool::IsCursorInTrimHandle(Block *block, qreal cursor_x)

app/widget/timelinewidget/tool/slip.cpp

@@ -80,7 +80,7 @@ void SlipTool::FinishDrag(TimelineViewMouseEvent *event)
     }
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 }

app/widget/timeruler/seekablewidget.cpp

@@ -116,7 +116,7 @@ void SeekableWidget::DeleteSelected()
       command->add_child(new MarkerRemoveCommand(marker));
     }
 
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
   }
 }
 
@@ -249,7 +249,7 @@ void SeekableWidget::mouseReleaseEvent(QMouseEvent *event)
   if (selection_manager_.IsDragging()) {
     MultiUndoCommand *command = new MultiUndoCommand();
     selection_manager_.DragStop(command);
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
   }
 
   if (GetSnapService()) {
@@ -364,7 +364,7 @@ void SeekableWidget::SetMarkerColor(int c)
     command->add_child(new MarkerChangeColorCommand(marker, c));
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 void SeekableWidget::ShowMarkerProperties()
@@ -614,7 +614,7 @@ void SeekableWidget::CommitResizeHandle()
     command->add_child(new WorkareaSetRangeCommand(workarea, workarea->range(), resize_item_range_));
   }
 
-  Core::instance()->undo_stack()->pushIfHasChildren(command);
+  Core::instance()->undo_stack()->push(command);
 }
 
 }

app/widget/viewer/viewer.cpp

@@ -557,7 +557,7 @@ void ViewerWidget::CreateAddableAt(const QRectF &f)
       shape->SetRect(f, s->GetVideoParams(), command);
     }
 
-    Core::instance()->undo_stack()->pushIfHasChildren(command);
+    Core::instance()->undo_stack()->push(command);
     SetGizmos(clip);
   }
 }

app/widget/viewer/viewerdisplay.cpp

@@ -946,7 +946,7 @@ bool ViewerDisplayWidget::OnMouseRelease(QMouseEvent *e)
       if (DraggableGizmo *draggable = dynamic_cast<DraggableGizmo*>(current_gizmo_)) {
         draggable->DragEnd(command);
       }
-      Core::instance()->undo_stack()->pushIfHasChildren(command);
+      Core::instance()->undo_stack()->push(command);
       gizmo_drag_started_ = false;
     }
     current_gizmo_ = nullptr;

app/window/mainwindow/mainwindow.cpp

@@ -85,6 +85,7 @@ MainWindow::MainWindow(QWidget *parent) :
   AppendTimelinePanel();
   audio_monitor_panel_ = new AudioMonitorPanel();
   scope_panel_ = new ScopePanel();
+  history_panel_ = new HistoryPanel();
 
   // HACK: The pixel sampler is closed by default, which signals to Core that
   //       it's no longer visible. However KDDockWidgets doesn't appear to
@@ -845,6 +846,8 @@ void MainWindow::SetDefaultLayout()
 
   // Bottom left - project panel
   addDockWidget(project_panel_, KDDockWidgets::Location_OnLeft, tool_panel_);
+  project_panel_->addDockWidgetAsTab(history_panel_);
+  project_panel_->raise();
 
   // Hidden panels
   pixel_sampler_panel_->close();

app/window/mainwindow/mainwindow.h

@@ -30,6 +30,7 @@
 #include "panel/panelmanager.h"
 #include "panel/audiomonitor/audiomonitor.h"
 #include "panel/curve/curve.h"
+#include "panel/history/historypanel.h"
 #include "panel/node/node.h"
 #include "panel/param/param.h"
 #include "panel/project/project.h"
@@ -157,6 +158,7 @@ private:
   ScopePanel* scope_panel_;
   QList<ViewerPanel*> viewer_panels_;
   MulticamPanel *multicam_panel_;
+  HistoryPanel *history_panel_;
 
 #ifdef Q_OS_WINDOWS
   unsigned int taskbar_btn_id_;