bpo-30928: Update idlelib/NEWS.txt to 2017 Sep 17. (#3635)

Lib/idlelib/NEWS.txt

@@ -3,6 +3,25 @@ Released on 2018-06-18?
 ========================
 
 
+bpo-31493: Fix code context update and font update timers.
+Canceling timers prevents a warning message when test_idle completes.
+
+bpo-31488: Update non-key options in former extension classes.
+When applying configdialog changes, call .reload for each feature class.
+Change ParenMatch so updated options affect existing instances attached
+to existing editor windows.
+
+bpo-31477: Improve rstrip entry in IDLE doc.
+Strip Trailing Whitespace strips more than blank spaces.
+Multiline string literals are not skipped.
+
+bpo-31480: fix tests to pass with zzdummy extension disabled. (#3590)
+To see the example in action, enable it on options extensions tab.
+
+bpo-31421: Document how IDLE runs tkinter programs.
+IDLE calls tcl/tk update in the background in order to make live
+interaction and experimentatin with tkinter applications much easier.
+
 bpo-bpo-31414: Fix tk entry box tests by deleting first.
 Adding to an int entry is not the same as deleting and inserting
 because int('') will fail.  Patch by Terry Jan Reedy.