RangeSelection2D not working as expected

[sogoogos]

Problem Description
I am trying to add the functionality to set ROI with a mouse using RangeSelection2D.
However, I am getting the following error after right-clicking the image displayed.

File "/Users/sshiozawa/.edm/envs/python-class/lib/python3.6/site-packages/chaco/linear_mapper.py", line 67, in map_data
    return (screen_val - self.low_pos) / self._scale + self.range.low
TypeError: unsupported operand type(s) for -: 'list' and 'float'

I see some old attempt here.

Reproduction Steps:
Run the following code with an image file and then right-click the image in the interface.

from skimage import io
import matplotlib.pyplot as plt
from traits.api import Array, Bool, Button, Enum, File, Float, HasTraits, Instance, Int, List, Str, on_trait_change
from traitsui.api import CheckListEditor, Group, Item, HGroup, spring, UItem, View
from chaco.api import Plot, ArrayPlotData
from chaco.tools.api import PanTool, RangeSelection2D, ZoomTool
from enable.api import BaseTool, ComponentEditor
class Image_GUI(HasTraits):
    # Define Parameters
    file_path = File(exists=True)
    img = Array()
    plot = Instance(Plot)
    # Define File Select Function
    def _file_path_changed(self):
        self.img = io.imread(self.file_path)
    # Define Plot Function
    def _plot_default(self):
        img = self.img
        # Show Plot if Image is loaded
        if len(img) > 0:
            # Show Plot
            data = ArrayPlotData(img=img)
            plot = Plot(data)
            plot.img_plot('img', origin='top left')
            # Set Aspect Ratio
            height, width, _ = img.shape
            plot.aspect_ratio = width / height
            plot.tools.append(RangeSelection2D(plot))
        else:
            plot = Plot()
        return plot
    # Run Plot Method if file is changed
    @on_trait_change('file_path')
    def create_new_plot(self):
        self.plot = self._plot_default()
    # Configure GUI Settings
    traits_view = View(Item('file_path'),
                       UItem('plot', editor=ComponentEditor()))
if __name__ == '__main__':
    img_gui = Image_GUI()
    img_gui.configure_traits()

Expected behavior:

[Describe expected behavior here]

OS, Python version:
macOS, Python 3.6.12

[rahulporuri]

i'm able to reproduce this on windows and see below for the full traceback

Traceback (most recent call last):
  File "C:\Users\rporuri\.edm\envs\chaco-test-3.6-pyqt5\lib\site-packages\enable\qt4\base_window.py", line 267, in mousePressEvent
    self.handler.mousePressEvent(event)
  File "C:\Users\rporuri\.edm\envs\chaco-test-3.6-pyqt5\lib\site-packages\enable\qt4\base_window.py", line 150, in mousePressEvent
    self._enable_window._handle_mouse_event(name + "_down", event)
  File "C:\Users\rporuri\.edm\envs\chaco-test-3.6-pyqt5\lib\site-packages\enable\abstract_window.py", line 382, in _handle_mouse_event
    self.component.dispatch(mouse_event, event_name)
  File "C:\Users\rporuri\.edm\envs\chaco-test-3.6-pyqt5\lib\site-packages\enable\component.py", line 957, in dispatch
    self._new_dispatch(event, suffix)
  File "C:\Users\rporuri\.edm\envs\chaco-test-3.6-pyqt5\lib\site-packages\enable\component.py", line 1008, in _new_dispatch
    tool.dispatch(event, suffix)
  File "C:\Users\rporuri\.edm\envs\chaco-test-3.6-pyqt5\lib\site-packages\enable\interactor.py", line 104, in dispatch
    self._dispatch_stateful_event(event, suffix)
  File "C:\Users\rporuri\.edm\envs\chaco-test-3.6-pyqt5\lib\site-packages\enable\interactor.py", line 120, in _dispatch_stateful_event
    handler(event)
  File "C:\Users\rporuri\.edm\envs\chaco-test-3.6-pyqt5\lib\site-packages\chaco\tools\range_selection_2d.py", line 182, in normal_right_down
    mapped_pos = self._map_data([(x_pos,y_pos)])[0][self.axis_index]
  File "C:\Users\rporuri\.edm\envs\chaco-test-3.6-pyqt5\lib\site-packages\chaco\tools\range_selection_2d.py", line 282, in _map_data
    return self.mapper.map_data(screen_pts)
  File "C:\Users\rporuri\.edm\envs\chaco-test-3.6-pyqt5\lib\site-packages\chaco\linear_mapper.py", line 65, in map_data
    return (screen_val - self.low_pos) / self._scale + self.range.low
TypeError: unsupported operand type(s) for -: 'list' and 'float'