Add support for bokeh theme (#2164)

* Add support for bokeh theme

* Update panel/pane/plot.py

Co-authored-by: Philipp Rudiger <prudiger@anaconda.com>

panel/pane/plot.py

@@ -10,6 +10,7 @@
 import param
 
 from bokeh.models import CustomJS, LayoutDOM, Model, Spacer as BkSpacer
+from bokeh.themes import Theme
 
 from ..io import remove_root
 from ..io.notebook import push
@@ -46,6 +47,9 @@ class Bokeh(PaneBase):
  Bokeh panes allow including any Bokeh model in a panel.
  """
 
+ theme = param.ClassSelector(default=None, class_=(Theme, str), doc="""
+ Bokeh theme to apply to the plot.""")
+
  priority = 0.8
 
  @classmethod
@@ -109,6 +113,10 @@ def _get_model(self, doc, root=None, parent=None, comm=None):
  remove_root(model, doc)
 
  self._models[ref] = (model, parent)
+
+ if self.theme:
+ doc.theme = self.theme
+
  return model