Nested macros should not be editable in-place if their parent macro is not editable in-place

Take for instance this wiki syntax:

{{velocity}}
before {{box}}{{/box}} after
{{/velocity}}

The role of the macro placeholder is to allow you to edit the macro even when the macro output is empty. But in this case the nested box macro cannot be edited directly (it is generated by the velocity macro) so it doesn't make sense to display the macro placeholder.