Fixed a crash when filtering all the files in a torrent

Changelog

@@ -23,6 +23,7 @@
     - BUGFIX: Progress column gets sorted on restart it is was during last execution
     - BUGFIX: Made ETA more reliable using stats instead of instant values
     - BUGFIX: Remove torrent from hard drive used to delete parent folder if empty
+    - BUGFIX: Fixed a crash when filtering all the files in a torrent
     - COSMETIC: Redesigned torrent properties a little
     - COSMETIC: Redesigned options a little
     - COSMETIC: Display more logs messages concerning features

src/PropListDelegate.h

@@ -143,6 +143,7 @@ class PropListDelegate: public QItemDelegate {
 
     QWidget* createEditor(QWidget *parent, const QStyleOptionViewItem &/* option */, const QModelIndex & index) const {
       if(index.column() != PRIORITY) return 0;
+      if(onlyOneItem(index)) return 0;
       QComboBox* editor = new QComboBox(parent);
       editor->setFocusPolicy(Qt::StrongFocus);
       editor->addItem(tr("Ignored"));
@@ -183,6 +184,17 @@ class PropListDelegate: public QItemDelegate {
       return textRect.size();
     }
 
+    bool onlyOneItem(const QModelIndex& index) const  {
+      const QAbstractItemModel *model = index.model();
+      unsigned int nbRows = model->rowCount();
+      if(nbRows == (unsigned int)1) return true;
+      for(unsigned int i=0; i<nbRows; ++i){
+        if((unsigned int)index.row() == i) continue;
+        if(model->data(model->index(i, PRIORITY)).toInt()) return false;
+      }
+      return true;
+    }
+
     public slots:
     void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const {
       QComboBox *combobox = static_cast<QComboBox*>(editor);