CompositeWidget types cannot be jslinked

[MarcSkovMadsen]

Panel 0.10.2 Bokeh 2.2.3

I currently styling all the Panel widgets and thus checking that all the parameters works. I've found that the DateRangeSlider does not work as documented at https://panel.holoviz.org/reference/widgets/DateRangeSlider.html#widgets-gallery-daterangeslider.

It turns out that the Direction and Tooltips works if I create separate python example. It's only the js-link that does not work

Minimal Example

import panel as pn
from datetime import date

vertical = pn.widgets.DateRangeSlider(
    name="Vertical",
    height=200, width=200,
    orientation="vertical")
vertical.start = date(2020, 1, 20)
vertical.end = date(2020, 2, 20)
vertical.value = (date(2020, 2, 18), date(2020, 2, 20))

pn.Column(vertical).servable()

[philippjfr]

DateRangeSlider is a composite widget which means some of its processing is handled in Python. I've repurposed this issue to be general.