added select all and deselect all functions

app/widget/panel/panel.cpp

@@ -67,6 +67,14 @@ void PanelWidget::GoToEnd()
 {
 }
 
+void PanelWidget::SelectAll()
+{
+}
+
+void PanelWidget::DeselectAll()
+{
+}
+
 void PanelWidget::SetTitle(const QString &t)
 {
   title_ = t;

app/widget/panel/panel.h

@@ -79,6 +79,10 @@ public:
 
   virtual void GoToEnd();
 
+  virtual void SelectAll();
+
+  virtual void DeselectAll();
+
 protected:
   /**
    * @brief Set panel's title

app/widget/timelineview/timelineview.cpp

@@ -199,6 +199,24 @@ void TimelineView::DisconnectTimelineNode()
   ConnectTimelineNode(nullptr);
 }
 
+void TimelineView::SelectAll()
+{
+  QList<QGraphicsItem*> all_items = items();
+
+  foreach (QGraphicsItem* i, all_items) {
+    i->setSelected(true);
+  }
+}
+
+void TimelineView::DeselectAll()
+{
+  QList<QGraphicsItem*> all_items = items();
+
+  foreach (QGraphicsItem* i, all_items) {
+    i->setSelected(false);
+  }
+}
+
 void TimelineView::SetTime(const int64_t time)
 {
   playhead_ = time;

app/widget/timelineview/timelineview.h

@@ -52,6 +52,10 @@ public:
 
   void DisconnectTimelineNode();
 
+  void SelectAll();
+
+  void DeselectAll();
+
 public slots:
   void SetTimebase(const rational& timebase);