GtkSpinButton without manually creating an adjustment. The value is
initially set to the minimum value and a page increment of 10 * step
is the default. The precision of the spin button is equivalent to the
precision of step. gtkSpinButtonNewWithRange(min, max, step, show = TRUE)minmaxstepstep
is a power of ten. If the resulting precision is not suitable for your
needs, use gtkSpinButtonSetDigits to correct it.