如圖所示, 當QSpinBox的值為最小值的時候, 不是顯示這個最小值, 而是顯示一個特殊的字符串用以代替這個最小值, 也只是QSpinBox的一個函數調用而已:
void QSpinBox::setSpecialValueText(const QString &specialText);
If set, the spin box will display this text instead of a numeric value whenever the current value is equal to minimum(). Typical use is to indicate that this choice has a special (default) meaning.