gh-93966: Remove the syntax error highlighting in the IDLE Shell on the next statement (#157595)

It stayed until the next syntax error.

Co-authored-by: André Roberge <andre.roberge@gmail.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: 3 people

Lib/idlelib/pyshell.py

@@ -705,6 +705,8 @@ def execfile(self, filename, source=None):
 
     def runsource(self, source):
         "Extend base class method: Stuff the source in the line cache first"
+        # Remove the highlighting of a previous syntax error (gh-93966).
+        self.tkconsole.text.tag_remove("ERROR", "1.0", "end")
         filename = self.stuffsource(source)
         # at the moment, InteractiveInterpreter expects str
         assert isinstance(source, str)
@@ -741,7 +743,6 @@ def showsyntaxerror(self, filename=None, **kwargs):
         """
         tkconsole = self.tkconsole
         text = tkconsole.text
-        text.tag_remove("ERROR", "1.0", "end")
         type, value, tb = sys.exc_info()
         if not issubclass(type, SyntaxError):
             tkconsole.resetoutput()

Misc/NEWS.d/next/IDLE/2026-09-15-22-10-17.gh-issue-93966.ch4fTB.rst

@@ -0,0 +1,2 @@
+The highlighting of a syntax error in the IDLE Shell is now removed when the
+next statement is entered, not only when the next syntax error occurs.