The component which caused the form to stop running.
Note:
Notice that this function doesn't fit in with newt's normal naming
convention. It is an older interface which will not work for all forms. It
was left in newt only for legacy applications. It is a simpler interface
than the new newt_form_run() though, and is still used quite often as a
result. When an application is done with a form, it destroys the form and
all of the components the form contains.