Use +/- instead of O/X or T/F

notebook/nbextensions.py

@@ -34,9 +34,9 @@ from traitlets.config.manager import BaseJSONConfigManager
 from tornado.log import LogFormatter
 
 # Constants for pretty print extension listing function.
-# Window doesn't support unicode characters in the commandline, so use T/F.
-GREEN_ENABLED = '\033[32mO\033[0m' if os.name != 'nt' else 'T'
-RED_DISABLED = '\033[31mX\033[0m' if os.name != 'nt' else 'F'
+# Window doesn't support coloring in the commandline
+GREEN_ENABLED = '\033[32m+\033[0m' if os.name != 'nt' else '+'
+RED_DISABLED = '\033[31m-\033[0m' if os.name != 'nt' else '-'
 
 DEPRECATED_ARGUMENT = object()
 #------------------------------------------------------------------------------