bpo-29910: IDLE no longer deletes a character after commenting out a region (#825)

This happened because shortcut has a class binding and 'break' was not returned.
Fix other potential conflicts between IDLE and default key bindings.

* Add news item

* Update NEWS
diff --git a/Lib/idlelib/calltips.py b/Lib/idlelib/calltips.py
index 4c5aea2..a8a3abe 100644
--- a/Lib/idlelib/calltips.py
+++ b/Lib/idlelib/calltips.py
@@ -47,6 +47,7 @@
     def force_open_calltip_event(self, event):
         "The user selected the menu entry or hotkey, open the tip."
         self.open_calltip(True)
+        return "break"
 
     def try_open_calltip_event(self, event):
         """Happens when it would be nice to open a CallTip, but not really