RangeSlider css_classes not being updated anymore

It seems in 0.12.7 the css_classes attribute of the RangeSlider is not being updated anymore by the callbacks. It was working in 0.12.6. In the example below, both the text input and the slider starts with the initial class as expected. When the slider changes, both should gain the sent-later class, but only the text input is gaining it…

from bokeh.io import curdoc
from bokeh.models import TextInput, RangeSlider
from bokeh.layouts import widgetbox
from bokeh.layouts import column
from bokeh.models import Div

div1 = Div(text="""
        <style>
        .sent-later {
            border-radius: 0.5em;
            padding: 1em;
            border: 3px solid #2397D8;
        }
        </style>
""")


def on_slider_change(attr, old, new):
    slider.css_classes.append('sent-later')
    text.css_classes.append('sent-later')
    print(slider.css_classes)
    print(text.css_classes)


text = TextInput(
        value=str(2),
        title='Population Beta:')

slider = RangeSlider(
        start=0,
        end=10,
        value=(0, 2),
        step=1,
        title='Population Beta')

slider.css_classes = []
slider.css_classes.append('initial')
text.css_classes = []
text.css_classes.append('initial')

slider.on_change('value', on_slider_change)

curdoc().add_root(column(div1, widgetbox(text, slider)))

[bryevdv]

@andresmrm The entire slider widget implementation was replace so that we could jettison jquery entirely. Thanks for your patience.

@mattpap I suspect it’s this:

https://github.com/bokeh/bokeh/blob/master/bokehjs/src/coffee/models/widgets/abstract_slider.coffee#L24-L26

Looks like render (whose super is what calls _render_classes) will only ever be called once.

[bryevdv]

The route suggested above works,I will create a PR