This question has been asked by Lisa Fiacco, but no answer.
I use a light yellow fill color on my fields. On Blur the field is checked for content and if it has a value then the fill color is changed to transparent. On form reset, a button, it clears all the field values and resets the fill color back to light yellow. It is easy to effect whole blocks of fields if you use a heretical naming convention.
// color for light yellow
color.ltYellow=["RGB", 1, 1, 0.667];
this.getField("myField").fillColor = color.ltYellow;