TableEditor: initialise events with is_event=True (#2041)

Initialise Events in Qt TableEditor with `is_event=True` in order to avoid an error in "sync_value"

traitsui/qt/table_editor.py

@@ -282,16 +282,16 @@ def init(self, parent):
 
         # Set up the required externally synchronized traits
         is_list = mode in ("rows", "columns", "cells")
-        self.sync_value(factory.click, "click", "to")
-        self.sync_value(factory.dclick, "dclick", "to")
+        self.sync_value(factory.click, "click", "to", is_event=True)
+        self.sync_value(factory.dclick, "dclick", "to", is_event=True)
         self.sync_value(factory.columns_name, "columns", is_list=True)
         self.sync_value(factory.selected, "selected", is_list=is_list)
         self.sync_value(
             factory.selected_indices, "selected_indices", is_list=is_list
         )
         self.sync_value(factory.filter_name, "filter", "from")
         self.sync_value(factory.filtered_indices, "filtered_indices", "to")
-        self.sync_value(factory.update_filter_name, "update_filter", "from")
+        self.sync_value(factory.update_filter_name, "update_filter", "from", is_event=True)
 
         self.auto_size = self.factory.auto_size