#17798: Allow IDLE to edit new files when specified on command line.

Lib/idlelib/EditorWindow.py

@@ -321,6 +321,8 @@ class EditorWindow(object):
                         per.insertfilter(color)
             else:
                 io.set_filename(filename)
+                self.good_load = True
+
         self.ResetColorizer()
         self.saved_change_hook()
         self.update_recent_files_list()

Misc/NEWS

@@ -135,6 +135,8 @@ Library
 IDLE
 ----
 
+- Issue #17798: Allow IDLE to edit new files when specified on command line.
+
 - Issue #14735: Update IDLE docs to omit "Control-z on Windows".
 
 - Issue #17585: Fixed IDLE regression. Now closes when using exit() or quit().