Terminal extension breaks cycling through history with multiline items

[wm75]

Stepping through the history with the Terminal extension enabled is done with the arrow up/down keys., but when a history item spanning multiple lines is encountered, the cursor gets "trapped" in the command and the arrow keys can no longer be used for further history navigation.

This behavior is accompanied by the following traceback in the terminal that idlex is being run from:

Exception in Tkinter callback
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/tkinter/__init__.py", line 1702, in __call__
    return self.func(*args)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/idlelib/multicall.py", line 176, in handler
    r = l[i](event)
  File "/Users/wolma/idlexl/idlexlib/extensions/Terminal.py", line 272, in key_down_callback
    if self.history_ismember():
  File "/Users/wolma/idlexl/idlexlib/extensions/Terminal.py", line 211, in history_ismember
    s = self.editwin.history._get_source('iomark', 'end-1c')
AttributeError: 'History' object has no attribute '_get_source'

[rutalreja-deloitte]

any resolution for this, had an important command in history that I want.
can I manually edit the file where the history is stored.
Terminal class in Terminal.py is called with parameter editwin which has editwin.text, cant find where terminal class is called