Fix idlelib comment typos reported by Mike on pull request 4803. (#4807)

diff --git a/Lib/idlelib/autocomplete_w.py b/Lib/idlelib/autocomplete_w.py
index 7c3138f..12113f9 100644
--- a/Lib/idlelib/autocomplete_w.py
+++ b/Lib/idlelib/autocomplete_w.py
@@ -246,7 +246,7 @@
         acw.wm_geometry("+%d+%d" % (new_x, new_y))
 
         if platform.system().startswith('Windows'):
-            # See issue 15786. When on windows platform, Tk will misbehaive
+            # See issue 15786. When on windows platform, Tk will misbehave
             # to call winconfig_event multiple times, we need to prevent this,
             # otherwise mouse button double click will not be able to used.
             acw.unbind(WINCONFIG_SEQUENCE, self.winconfigid)