gtk:adjustment-clamp-page (adjustment lower upper)

adjustment -- a gtk:adjustment object
lower -- a double float with the lower value
upper -- a double float with the upper value

Updates the adjustment value to ensure that the range between lower and upper is in the current page. If the range is larger than the page size, then only the start of it will be in the current page. A "changed" signal will be emitted if the value is changed.