It would be nice to have this info in the list of used templates.
It would be enough to build a tree-like debug info, without the need to show boxes inline with the html

Anaylisis:

eztemplate::loaduriroot is the function calling eZTemplate::appendTemplateToStatistic, which records tpl usage

loaduriroot is called at least in 3 functions by eztemplate itself (load, fetch and processuri) and once by ezobjectforwarder

The "parent tpl" would have to be traced though these calls, unless there is some global variable already holding its name or filename...