Tabulator selection with pd.MultiIndex is not working in Panel 1.5.1

[hoxbro]

Worked in Panel 1.5, Without doing a git bisect likely it is #7304

Two examples:

import panel as pn
import pandas as pd

pn.extension("tabulator")

index = pd.MultiIndex.from_tuples([(i, j) for i in range(10) for j in range(10)], names=["A", "B"])
df = pd.DataFrame(index=index, data={"C": range(100)})

w = pn.widgets.Tabulator(df, pagination="remote")
w.on_click(lambda x: print(x))
w.servable()

Traceback

message: Message 'PATCH-DOC' content: {'events': [{'kind': 'MessageSent', 'msg_type': 'bokeh_event', 'msg_data': {'type': 'event', 'name': 'cell-click', 'values': {'type': 'map', 'entries': [['model', {'id': 'p1220'}], ['column', 'B'], ['row', 9]]}}}]}
 error: ValueError('The Tabulator widget expects the provided `value` Pandas DataFrame to have unique indexes, in particular when it has to deal with click or edit events. Found this duplicate index: 9')
Traceback (most recent call last):
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/server/protocol_handler.py", line 94, in handle
    work = await handler(message, connection)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/server/session.py", line 94, in _needs_document_lock_wrapper
    result = func(self, *args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/server/session.py", line 286, in _handle_patch
    message.apply_to_document(self.document, self)
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/protocol/messages/patch_doc.py", line 104, in apply_to_document
    invoke_with_curdoc(doc, lambda: doc.apply_json_patch(self.payload, setter=setter))
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/document/callbacks.py", line 453, in invoke_with_curdoc
    return f()
           ^^^
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/protocol/messages/patch_doc.py", line 104, in <lambda>
    invoke_with_curdoc(doc, lambda: doc.apply_json_patch(self.payload, setter=setter))
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/document/document.py", line 391, in apply_json_patch
    DocumentPatchedEvent.handle_event(self, event, setter)
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/document/events.py", line 244, in handle_event
    event_cls._handle_event(doc, event)
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/document/events.py", line 279, in _handle_event
    cb(event.msg_data)
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/document/callbacks.py", line 400, in trigger_event
    model._trigger_event(event)
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/util/callback_manager.py", line 111, in _trigger_event
    self.document.callbacks.notify_event(cast(Model, self), event, invoke)
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/document/callbacks.py", line 262, in notify_event
    invoke_with_curdoc(doc, callback_invoker)
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/document/callbacks.py", line 453, in invoke_with_curdoc
    return f()
           ^^^
  File "/home/shh/miniconda3/envs/holoviz/lib/python3.12/site-packages/bokeh/util/callback_manager.py", line 107, in invoke
    cast(EventCallbackWithEvent, callback)(event)
  File "/home/shh/projects/holoviz/repos/panel/panel/reactive.py", line 572, in _server_event
    self._comm_event(doc, event)
  File "/home/shh/projects/holoviz/repos/panel/panel/reactive.py", line 559, in _comm_event
    state._handle_exception(e)
  File "/home/shh/projects/holoviz/repos/panel/panel/io/state.py", line 468, in _handle_exception
    raise exception
  File "/home/shh/projects/holoviz/repos/panel/panel/reactive.py", line 557, in _comm_event
    self._process_bokeh_event(doc, event)
  File "/home/shh/projects/holoviz/repos/panel/panel/reactive.py", line 494, in _process_bokeh_event
    self._process_event(event)
  File "/home/shh/projects/holoviz/repos/panel/panel/widgets/tables.py", line 1343, in _process_event
    self._validate_iloc(idx, iloc)
  File "/home/shh/projects/holoviz/repos/panel/panel/widgets/tables.py", line 1300, in _validate_iloc
    raise ValueError(
ValueError: The Tabulator widget expects the provided `value` Pandas DataFrame to have unique indexes, in particular when it has to deal with click or edit events. Found this duplicate index: 9

import panel as pn
import pandas as pd

pn.extension("tabulator")

index = pd.MultiIndex.from_tuples([(i, j) for i in range(10) for j in range(10)], names=["A", "B"])
df = pd.DataFrame(index=index, data={"C": range(100)})

w = pn.widgets.Tabulator(df, pagination="remote", selectable='checkbox')
w.servable()

b = pn.widgets.Button(name='Print selected rows', on_click=lambda x: print(w.selection))
b.servable()

Will just return an empty list