* of load(), save() and defaults() (preferably at the end of the derived function, since they call setChangedState(false)).
*
* The following widgets can be handled for now:
+ * - QGroupBox (isChecked())
* - QAbstractButton (isChecked(), e.g. for QCheckBox and QRadioButton)
* - QLineEdit, QTextEdit (text())
* - QComboBox (currentIndex())