Get naked '?' to work, and in-spec with the new inputsplitter design.

IPython/core/interactiveshell.py

@@ -32,6 +32,7 b' from contextlib import nested'
 from IPython.config.configurable import Configurable
 from IPython.core import debugger, oinspect
 from IPython.core import history as ipcorehist
+from IPython.core import page
 from IPython.core import prefilter
 from IPython.core import shadowns
 from IPython.core import ultratb
@@ -2115,6 +2116,10 b' class InteractiveShell(Configurable, Magic):'
         if self.quiet:
             return True
         return ask_yes_no(prompt,default)
+    
+    def show_usage(self):
+        """Show a usage message"""
+        page.page(IPython.core.usage.interactive_usage)
 
     #-------------------------------------------------------------------------
     # Things related to IPython exiting

IPython/core/prefilter.py

@@ -960,7 +960,7 b' class HelpHandler(PrefilterHandler):'
                 #print 'line:<%r>' % line  # dbg
                 self.shell.magic_pinfo(line)
             else:
-                page.page(self.shell.usage, screen_lines=self.shell.usable_screen_length)
+                self.shell.show_usage()
             return '' # Empty string is needed here!
         except:
             raise