Can't update fill_color in PolyDraw stream

HoloViews
1

I have tried many methods to dynamically change the fill color in a PolyDraw stream, but none seem to work. For example, in the following code, changing the color in the Selector has no effect on the fill color of the polygons:

Screen Shot 2021-11-04 at 5.51.55 PM
Screen Shot 2021-11-04 at 5.51.55 PM683×648 54.9 KB

2

Here is the code:

#%%

import holoviews as hv
from holoviews import opts, streams
import panel as pn
import param
hv.extension('bokeh')

#%%

class ClassPoly(param.Parameterized):

    colors = [ 'red', 'blue', 'green', 'yellow' ]
    class_selector = param.Selector(colors, default='red' )
    poly = hv.Polygons([]).opts( fill_alpha = 1.0 )
    poly_stream = streams.PolyDraw( source=poly, show_vertices=True,
                                    styles= dict( fill_alpha=1.0, fill_color = [ "black" ] ) )

    @param.depends('class_selector', watch=True)
    def update_selection(self):
        class_color = self.class_selector
        self.poly_stream.styles.update( fill_color = [ class_color ]  )


#%%

cp = ClassPoly()
pn.Row( cp.param.class_selector, cp.poly )

#%%