Tweaked Make Selected into Reference.

Having dupes from ref folders (which makes ref switching impossible) would make
the new feature glitchy (selection would be emptied). Now, in cases where the action
results in nothing being changed, the selection stays intact. [#222]

core/engine.py

@@ -325,14 +325,15 @@ class Group:
     
     def switch_ref(self, with_dupe):
         if self.ref.is_ref:
-            return
+            return False
         try:
             self.ordered.remove(with_dupe)
             self.ordered.insert(0, with_dupe)
             self._percentage = None
             self._matches_for_ref = None
+            return True
         except ValueError:
-            pass
+            return False
     
     dupes = property(lambda self: self[1:])