Fix outdated comment re: event handlers in test_backends_interactive.

The comment should have been updated together with the event processing
refactor.

Author: anntzer

lib/matplotlib/tests/test_backends_interactive.py

@@ -77,10 +77,8 @@ def _get_testable_interactive_backends():
 # The source of this function gets extracted and run in another process, so it
 # must be fully self-contained.
 # Using a timer not only allows testing of timers (on other backends), but is
-# also necessary on gtk3 and wx, where a direct call to key_press_event("q")
-# from draw_event causes breakage due to the canvas widget being deleted too
-# early.  Also, gtk3 redefines key_press_event with a different signature, so
-# we directly invoke it from the superclass instead.
+# also necessary on gtk3 and wx, where directly processing a KeyEvent() for "q"
+# from draw_event causes breakage as the canvas widget gets deleted too early.
 def _test_interactive_impl():
     import importlib
     import importlib.util