In the ImageWidget constructor, there is an option to specify the figure shape via the figure_shape argument. You should also be able to specify a 'shape' field in figure_kwargs (that is the point of figure_kwargs -- to customize the Figure object construction).
However, use figure_kwargs to do this, the constructor will throw an error.

We need to adjust the logic to
(1) See if the user specified a figure_shape
(2) If not, see if the user specified a 'shape' variable in figure_kwargs

We then use one set of streamlined statements to construct the Figure object.