* system/fluents.py: Fixed a bug where the the application tried to load

a toolbar from None

 * system/plots.py: Fixed MainView.insert_view that was a no-op when in large
   view.

 * system/dataset.py: Changed __str__ of dataset to also show names of dimensions.

system/fluents.py

@@ -97,8 +97,12 @@ class FluentApp:
         window = self.widget_tree.get_widget('plot_toolbar_dock')
         if self._plot_toolbar:
             window.remove(self._plot_toolbar)
-            
-        self._plot_toolbar = view.get_toolbar()
+        
+        if view:    
+            self._plot_toolbar = view.get_toolbar()
+        else:
+            self._plot_toolbar = None
+
         if self._plot_toolbar:
             window.add(self._plot_toolbar)
 
@@ -127,6 +131,8 @@ class FluentApp:
         return self.navigator_view
 
     # Event handlers.
+    # These methods are called by the gtk framework in response to events and
+    # should not be called directly.
 
     def on_single_view(self, *ignored):
         self['main_view'].goto_large()