labelWidget label; interactive widgets also use it for ID generation. A ## suffix can distinguish IDs without displaying the suffix.
flagsMutable bit field in flags[0]; the checkbox sets or clears flags_value bits. Pass Int32Array storage, not a JS scalar; native access uses the supplied backing memory.
flags_valueBit mask tested and toggled in flags[0] by the checkbox.
True if the widget changed the supplied value; false if it remained unchanged.
Display a checkbox that sets or clears a group of bits in an integer flag value.