The QSpinBox class provides a spin box widget, sometimes called up-down widget, little arrows widget or spin button. ... The spin box clamps the value within a numeric range, see QRangeControl for details. ... Most spin boxes are directional, but QSpinBox can also operate as a circular spin box, i.e. if the range is 0-99 and the current value is 99, clicking Up will give 0. ... This virtual function is used by the spin box whenever it needs to interpret the text entered by the user as a value. ...