The idea is that a SplitterHeaderBar will be added in the
near future so the checks for the parent widget could be
wrong.
If instead of checking for a specific widget we check for
anything and walk to the parent list untill we find
a TerminalWidget seems sane, and safer.
Phabricator messed with this review and send the wrong diff together (because of the same parent)
so I'm rephrasing it.