BUG: DataBox Overlay Causing Component to Disappear

[skailasa]

Problem Description

Resizing component containing DataBox failing due to bug in position update. It causes the component to 'disappear'

This is due to the fact that when updating the position, the first element of the transpose of tmp is taken which is the wrong dimension, tmp is a (1,2) array.meaning that first element of its transpose is just a (1,1) array leading to an error when attempting to unpack these values into xs and ys in map_data

    # lines 144-152 in DataBox.py
    @on_trait_change('position,position_items')
    def _update_position(self):
        if self._updating:
            return
        tmp = self.component.map_data(self.position)
        if len(tmp.shape) == 2:
            tmp = tmp.T[0]
        self._data_position = tmp
        self.trait_property_changed("data_position", self._data_position)

Reproduction Steps:

# Create traitsui view, with a component containing a DataBox

class Demo(HasTraits):
  
  plot = Instance(Plot)

  def _plot_default(self):
  	data = ...
  	plot = Plot(data)

  	databox_overlay = DataBox(component=plot)
  	move_tool = MoveTool(component=databox_overlay)
  	databox_overlay.tools.append(move_tool)

  	plot.overlays.append(databox_overlay)


  view = View(
  Item('plot')
  )


if __name__ == "__main__":
  Demo().configure_traits()

Expected behavior:

No errors when resizing plot component with DataBox overlay

OS, Python version:
MacOS Python 3.60