bpo-38944: Escape key now closes IDLE completion windows. (GH-17419)

diff --git a/Lib/idlelib/autocomplete_w.py b/Lib/idlelib/autocomplete_w.py
index 5035e06..f20b633 100644
--- a/Lib/idlelib/autocomplete_w.py
+++ b/Lib/idlelib/autocomplete_w.py
@@ -17,7 +17,7 @@
 # before the default specific IDLE function
 KEYPRESS_SEQUENCES = ("<Key>", "<Key-BackSpace>", "<Key-Return>", "<Key-Tab>",
                       "<Key-Up>", "<Key-Down>", "<Key-Home>", "<Key-End>",
-                      "<Key-Prior>", "<Key-Next>")
+                      "<Key-Prior>", "<Key-Next>", "<Key-Escape>")
 KEYRELEASE_VIRTUAL_EVENT_NAME = "<<autocompletewindow-keyrelease>>"
 KEYRELEASE_SEQUENCE = "<KeyRelease>"
 LISTUPDATE_SEQUENCE = "<B1-ButtonRelease>"