Issue #26386: Fixed ttk.TreeView selection operations with item id's
containing spaces.
diff --git a/Lib/lib-tk/ttk.py b/Lib/lib-tk/ttk.py
index f7d0433..3f6f79b 100644
--- a/Lib/lib-tk/ttk.py
+++ b/Lib/lib-tk/ttk.py
@@ -1394,7 +1394,9 @@
 
     def selection(self, selop=None, items=None):
         """If selop is not specified, returns selected items."""
-        return self.tk.call(self._w, "selection", selop, items)
+        if isinstance(items, basestring):
+            items = (items,)
+        return self.tk.splitlist(self.tk.call(self._w, "selection", selop, items))
 
 
     def selection_set(self, items):