Get a different (non default) widget when using param in parameterized class (holoviz param panel)

Question

I use a parameterized class to build my Panel dashboard.

I would like to use a CrossSelector but this selector does not seem to be available when looking at the options that library Param gives. It only seems to have a ListSelector.

How do i get this CrossSelector using Param?

import param
import panel as pn

pn.extension()

class ValveExplorer(param.Parameterized):

    selected_features = param.ListSelector(
        default=[1, 3],
        objects=[1, 2, 3, 4],
    )

valve_explorer = ValveExplorer()  

# show list selector
pn.Row(valve_explorer.param['selected_features'])

This results in the following default ListSelector but I don't want this one. I would like to get a CrossSelector instead:

Answer 1

Param has a default widget for every Selector, but you can change this.

You can override this default widget as follows to get the CrossSelector in your example by using pn.Param():

pn.Row(pn.Param(
    valve_explorer.param['selected_features'], 
    widgets={'selected_features': pn.widgets.CrossSelector}
))

A similar solution found on SO is using pn.panel():

pn.Row(pn.panel(
    valve_explorer.param['selected_features'], 
    widgets={'selected_features': pn.widgets.CrossSelector}
))

See more documentation on using Param with Panel here:
https://panel.pyviz.org/user_guide/Param.html