PlaylistView: Use Qt::CopyAction for drag

Fixes #1815

src/playlist/playlistview.cpp

@@ -58,6 +58,7 @@
 #include <QScrollBar>
 #include <QtEvents>
 #include <QSettings>
+#include <QDrag>
 
 #include "includes/qt_blurimage.h"
 #include "core/song.h"
@@ -1620,3 +1621,11 @@ void PlaylistView::RatingHoverOut() {
   }
 
 }
+
+void PlaylistView::startDrag(const Qt::DropActions drop_actions) {
+
+  QDrag *drag = new QDrag(this);
+  drag->setMimeData(model()->mimeData(selectedIndexes()));
+  drag->exec(drop_actions, Qt::CopyAction);
+
+}

src/playlist/playlistview.h

@@ -156,6 +156,7 @@ class PlaylistView : public QTreeView {
   // QAbstractItemView
   void rowsInserted(const QModelIndex &parent, const int start, const int end) override;
   void closeEditor(QWidget *editor, const QAbstractItemDelegate::EndEditHint hint) override;
+  void startDrag(const Qt::DropActions drop_actions) override;
 
  private Q_SLOTS:
   void Update() { update(); }