© J.C. Kessels 2009
Fill all the gaps by moving (shifting) items to the beginning of the zone.
This will perfectly fill all the gaps and will preserve the sorting order of the files.
- A tiny little gap somewhere at the beginning of the zone will cause all items
above the gap to be moved (shifted). In this case MoveDownFill() is only a little
faster than a full SortBy***(). However, if the gap happens to be further into
the zone then MoveDownFill() will save time.
# Fill gaps with items from above.
See also: FastFill