SettingsAbstractWidget::saveState return Boolean, indicating change of setting
Function SettingsAbstractWidget::saveState() has been refactored from returning nothing
to returning a Boolean value where 'true' indicates that the state of a given setting
has changed and 'false' indicates no such change (or an error condition).
In most cases, implementations of this function in descending classes of
SettingsAbstractWidget can rely on the Preferences class's setting
function's Boolean return values.