Differentiate macros with empty content from macros without content

Macros with empty content:

{{xyz}}{{/xyz}}

generate:

<!--startmacro:xyz|-||-|--><!--stopmacro-->

while macros without content:

{{xyz/}}

generate:

<!--startmacro:xyz|-|--><!--stopmacro-->

Currently the WYSIWYG editor understands only the first form.