To use one global a4j:status : you can give it an id, and refer to it explicitly from ajax tags
Using the status attribute to refer to a given a4j:status in every ajax tag I use on the page is not acceptable. The case is even worse if the file with the nested regions is a template for example:
In foo1,2,3 there can be several ajax tags and in the template itself too.
It would simplify things if a4j:region had a status attribute too.
I'm not really sure why <a4j:region> doesn't have a status attribute. <a4j:form> does have one.
yes.. that was missed during design and will be corrected in RF 4.
Currently in order to make it easier and more reusable I could only suggest to create facelet tag which will wrap child content with region and plce status inside that region. That will allow to use single tag to add region and status in the same time.