Add a mechanism to specify default loaders when loading, not just for saving. Make the off plugin the default loader for .off files so that lcc_plugin doesn't come first in the list.

Polyhedron/demo/Polyhedron/MainWindow.cpp

@@ -1107,7 +1107,12 @@ void MainWindow::open(QString filename)
       if ( !io_plugin->canLoad() ) continue;
       all_items << io_plugin->name();
       if ( file_matches_filter(io_plugin->loadNameFilters(), filename.toLower()) )
-        selected_items << io_plugin->name();
+      {
+        if(io_plugin->isDefaultLoader(fileinfo.completeSuffix()))
+          selected_items.prepend(io_plugin->name());
+        else
+          selected_items << io_plugin->name();
+      }
     }
   }
   else

Polyhedron/demo/Polyhedron/Plugins/IO/OFF_io_plugin.cpp

@@ -32,6 +32,13 @@ public:
       return true; 
     return false;
   }
+  bool isDefaultLoader(const QString& name) const 
+  { 
+    qDebug()<<name;
+    if(name == QString("off")) 
+      return true; 
+    return false;
+  }
   QString name() const { return "off_plugin"; }
   QString nameFilters() const { return "OFF files (*.off);;Wavefront OBJ (*.obj)"; }
   bool canLoad() const;

Polyhedron/demo/Polyhedron/Plugins/IO/lcc_io_plugin.cpp

@@ -62,9 +62,8 @@ public:
   }
   
   
-  bool canSave(const CGAL::Three::Scene_item*){return true;}
+  bool canSave(const CGAL::Three::Scene_item*){return false;}
   bool save(const CGAL::Three::Scene_item*, QFileInfo fileinfo){
-    qDebug() << fileinfo.fileName() << "Implement me, you fool !";
     return false;
   }
   

Three/include/CGAL/Three/Polyhedron_demo_io_plugin_interface.h

@@ -70,10 +70,15 @@ public:
   //! This must be overriden.
   virtual bool save(const Scene_item*, QFileInfo fileinfo) = 0;
   
-  //! If this returns `true`, then the loader will be chosen as defaultin the
+  //! If this returns `true`, then the loader will be chosen as default in the
   //! list of available loaders when saving a file, which means it will be the 
   //! first in the list.
   virtual bool isDefaultLoader(const Scene_item*) const { return false; }
+  //! If this returns `true`, then the loader will be chosen as default in the
+  //! list of available loaders when loading a file, which means it will be the 
+  //! first in the list.
+  //! @param name is the extension without the dot (e.g. "off" for a .off file)
+  virtual bool isDefaultLoader(const QString& name) const { return false; }
 };
 }
 }