GtkSpinButton::set_wrap

Where set_wrap() is set to true, the spinbutton having displayed the upper bound of its value range will return to the lower bound on the next step increment. In other words, if the range is 1 to 10, 1 will follow 10 in the display area when the up arrow is pressed.

The default setting is false, which greys out the appropriate arrow when the lower or upper bound of the range is reached.