bpo-37903: IDLE: Shell sidebar with prompts (GH-22682)

The first followup will change shell indents to spaces.
More are expected.

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
diff --git a/Lib/idlelib/history.py b/Lib/idlelib/history.py
index ad44a96..7ce0925 100644
--- a/Lib/idlelib/history.py
+++ b/Lib/idlelib/history.py
@@ -74,13 +74,13 @@ def fetch(self, reverse):
                 else:
                     if self.text.get("iomark", "end-1c") != prefix:
                         self.text.delete("iomark", "end-1c")
-                        self.text.insert("iomark", prefix)
+                        self.text.insert("iomark", prefix, "stdin")
                     pointer = prefix = None
                 break
             item = self.history[pointer]
             if item[:nprefix] == prefix and len(item) > nprefix:
                 self.text.delete("iomark", "end-1c")
-                self.text.insert("iomark", item)
+                self.text.insert("iomark", item, "stdin")
                 break
         self.text.see("insert")
         self.text.tag_remove("sel", "1.0", "end")