Thanks for the tip. I tried this, but it does seem to (as you say) append the rows to the bottom. I really want to replace the existing content, or just update a single row. I can update a single item in a row without too much trouble, and I can actually insert a row without problems, but for example if I try to delete a row with this:
gridScreen.content.removeChildIndex(existingRow)
This leaves images from the deleted row rendered on top of the first row. (!?) The same thing happens if I use replaceChildren.
Maybe it's because all my rows are different sizes... I recalculate the row sizes after an add/delete, but that isn't helping with the rows-on-top-of-rows bug. The first row is a series of large banners that fill the width of the screen; the rest of the rows are smaller rectangles or square posters.
For now my only solution is the extreme one: I have to create a whole new rowList object, assign the new content to that, and make it visible (and the old one !visible).
It'd be nice if rowList could be updated in place without these graphics glitches! Hence the need for a "redraw" command...