Avoid + icon when dragging files from project tree

Change-Id: I286f6bfbb647111b6ae9ad90c5171499382b2e71
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/plugins/projectexplorer/projectmodels.cpp

@@ -488,6 +488,11 @@ void FlatModel::reset()
     endResetModel();
 }
 
+Qt::DropActions FlatModel::supportedDragActions() const
+{
+    return Qt::MoveAction;
+}
+
 QStringList FlatModel::mimeTypes() const
 {
     return Utils::FileDropSupport::mimeTypesForFilePaths();

src/plugins/projectexplorer/projectmodels.h

@@ -65,6 +65,7 @@ public:
 
     void reset();
 
+    Qt::DropActions supportedDragActions() const;
     QStringList mimeTypes() const;
     QMimeData *mimeData(const QModelIndexList &indexes) const;