SpinButton.addOnOutput

Emitted to tweak the formatting of the value for display.

// show leading zeros
static gboolean
on_output (GtkSpinButton *spin,
gpointer       data)
{
GtkAdjustment *adjustment;
char *text;
int value;

adjustment = gtk_spin_button_get_adjustment (spin);
value = (int)gtk_adjustment_get_value (adjustment);
text = g_strdup_printf ("%02d", value);
gtk_spin_button_set_text (spin, text):
g_free (text);

return TRUE;
}