right click menu in node view for adding nodes

ui/nodeui.cpp

@@ -29,8 +29,8 @@ NodeUI::NodeUI() :
 
 NodeUI::~NodeUI()
 {
-  if (scene() != nullptr) {
-    scene()->removeItem(proxy_);
+  if (proxy_ != nullptr) {
+    proxy_->setParentItem(nullptr);
   }
 }
 
@@ -164,6 +164,7 @@ void NodeUI::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
   if (clicked_socket_ > -1) {
 
     bool line_is_touching_node = false;
+    drag_destination_ = nullptr;
 
     QPointF drag_line_end = event->scenePos();
 
@@ -234,6 +235,8 @@ void NodeUI::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
 {
   if (clicked_socket_ > -1) {
     scene()->removeItem(drag_line_);
+    delete drag_line_;
+
     event->accept();
 
     if (drag_destination_ != nullptr) {

ui/nodeview.cpp

@@ -4,6 +4,9 @@
 #include <QScrollBar>
 #include <QDebug>
 
+#include "ui/menu.h"
+#include "nodes/node.h"
+
 NodeView::NodeView(QGraphicsScene *scene, QWidget *parent) :
   QGraphicsView(scene, parent),
   hand_moving_(false)
@@ -20,6 +23,11 @@ void NodeView::mousePressEvent(QMouseEvent *event)
   if (event->button() == Qt::MidButton) {
     hand_moving_ = true;
     drag_start_ = event->pos();
+  } else if (event->button() == Qt::RightButton && scene()->itemAt(mapToScene(event->pos()), QTransform()) == nullptr) {
+
+    // If the user clicked with the right button on empty space, show the context menu
+    emit RequestContextMenu();
+
   } else {
     QGraphicsView::mousePressEvent(event);
   }

ui/nodeview.h

@@ -3,11 +3,16 @@
 
 #include <QGraphicsView>
 
+#include "timeline/tracktypes.h"
+
 class NodeView : public QGraphicsView {
   Q_OBJECT
 public:
   NodeView(QGraphicsScene *scene, QWidget* parent = nullptr);
 
+signals:
+  void RequestContextMenu();
+
 protected:
   virtual void mousePressEvent(QMouseEvent *event) override;
   virtual void mouseMoveEvent(QMouseEvent *event) override;

ui/timelineview.cpp

@@ -2741,7 +2741,7 @@ void TimelineView::mouseMoveEvent(QMouseEvent *event) {
           // cursor is hovering over a clip
 
           // check if the clip and transition are both the same sign (meaning video/audio are the same)
-          if (track_list_->type() == ParentTimeline()->transition_tool_side) {
+          if (track_list_->type() == olive::node_library[ParentTimeline()->transition_tool_meta]->subtype()) {
 
             // the range within which the transition tool will assume the user wants to make a shared transition
             // between two clips rather than just one transition on one clip