Version-Release number of selected component:
pitivi-0.99-1.fc27

Additional info:
reporter:       libreport-2.9.3
cmdline:        python3 /usr/bin/pitivi
crash_function: begin
exception_type: pitivi.undo.undo.UndoWrongStateError
executable:     /usr/bin/pitivi
kernel:         4.13.12-300.fc27.x86_64
runlevel:       N 5
type:           Python3
uid:            1000

Truncated backtrace:
undo.py:215:begin:pitivi.undo.undo.UndoWrongStateError: ('Toplevel operation started as suboperation', [Video position change: []])

Traceback (most recent call last):
  File "/usr/lib64/python3.6/site-packages/matplotlib/backends/backend_gtk3.py", line 234, in button_press_event
    FigureCanvasBase.button_press_event(self, x, y, event.button, guiEvent=event)
  File "/usr/lib64/python3.6/site-packages/matplotlib/backend_bases.py", line 1909, in button_press_event
    self.callbacks.process(s, mouseevent)
  File "/usr/lib64/python3.6/site-packages/matplotlib/cbook.py", line 549, in process
    proxy(*args, **kwargs)
  File "/usr/lib64/python3.6/site-packages/matplotlib/cbook.py", line 416, in __call__
    return mtd(*args, **kwargs)
  File "/usr/lib64/python3.6/site-packages/pitivi/timeline/elements.py", line 292, in _mpl_button_press_event_cb
    toplevel=True)
  File "/usr/lib64/python3.6/site-packages/pitivi/undo/undo.py", line 215, in begin
    raise UndoWrongStateError("Toplevel operation started as suboperation", self.stacks)
pitivi.undo.undo.UndoWrongStateError: ('Toplevel operation started as suboperation', [Video position change: []])

Local variables in innermost frame:
toplevel: True
finalizing_action: None
action_group_name: 'Move keyframe curve segment'
self: <undo.UndoableActionLog object at 0x7fbee83f09d8 (pitivi+undo+undo+UndoableActionLog at 0x55ce110b90a0)>