The delegate callback to execute when invoking the command.
This widget to aid method chaining.
These are the fields within the callback's CommandArgs parameter which are populated by this method when the callback is executed.
$(PARAM_TABLE $(PARAM_ROW CommandArgs.element, The column that executed the callback.) $(PARAM_ROW CommandArgs.uniqueData, The internal id of the tree view (An implementation detail that's not very useful).) $(PARAM_ROW CommandArgs.callback, The callback which was executed.) )
Set the column command to be executed when clicking on the heading.