title: Emit signal if all children widgets lose focus
body: <p>I have a <code>QStackedWidget</code> which holds several pages full of various <code>QLineEdit</code> and <code>QComboBox</code> children. I want to emit a signal whenever the <code>QStackedWidget</code> no longer has <strong>any</strong> child with focus (given that a child had focus to begin with). So moving from child to child will not emit a signal, but once a widget is selected outside of the <code>QStackedWidget</code>, a signal is emitted. Any advice on how to implement this? I've looked at <code>InstallEventFilter</code> and <code>QSignalMapper</code>, but neither of those appear to fit my needs. Any advice would be appreciated.</p>