replace _update_mixed_state with call to _on_glue_value_changed

jdaviz/core/template_mixin.py

@@ -4401,25 +4401,17 @@ def is_mixed(self, glue_values):
         return len(np.unique(glue_values, axis=0)) > 1
 
     def _update_mixed_state(self):
-        if len(self.linked_states) <= 1:
-            mixed = False
-        else:
+        if self._processing_change_from_glue:
+            return
+
+        if len(self.linked_states) >= 1:
             current_glue_values = []
             for state in self.linked_states:
                 current_glue_values.append(self._get_glue_value(state))
-            mixed = self.is_mixed(current_glue_values)
-            # ensure the value corresponds to the first entry, this prevents the case where a glue
-            # change to one of the linked_states changes the value that will be adopted when
-            # unmixing something in mixed state and results in more consistent and predictable
-            # behavior
-            self._processing_change_from_glue = True
-            first_value = current_glue_values[0]
-            if isinstance(first_value, np.float32):
-                first_value = first_value.astype(np.float64)
-            self.value = first_value
-            self._processing_change_from_glue = False
-        self.sync = {**self.sync,
-                     'mixed': mixed}
+
+        if len(current_glue_values) and current_glue_values[0] is not None:
+            # sync the initial value of the widget, avoiding recursion
+            self._on_glue_value_changed(current_glue_values[0])
 
     def _on_value_changed(self, msg):
         if self._processing_change_from_glue: