Respond only once property of HTML Area does not work when a scroll/grid is involved.
Peoplebook says, when we select 'Respond Only Once' property of HTML Area, it will not added in the ajax request, and which means, it will not refreshed when other field change events are invoked.
This seems to be working fine when the field change event does not involve and addition or deletion of rows in grid.
The HTML Area gets refreshed when we involve any row insert or row delete in a grid.