Initialize links on ElementPlot when it is top-level

Author: philippjfr

holoviews/plotting/bokeh/element.py

@@ -1380,6 +1380,9 @@ def initialize_plot(self, ranges=None, plot=None, plots=None, source=None):
         for cb in self.callbacks:
             cb.initialize()
 
+        if self.top_level:
+            self.init_links()
+
         if not self.overlaid:
             self._set_active_tools(plot)
             self._process_legend()