The "Write continuously" option is documented in the Slider Gadget section of the groov Build and View User's Guide in the Slider Gadget section. (It's on page 100 of the version that's on our website dated July 2017.)
Its definition is "Check the box to continually write values as the slider is dragged. If unchecked, value is written once you let go."
Is there another page (namely, the page depicted in your screenshot) where it would help to have the info also?
Opto 22 Documentation Team member