A Row-grid object is a row or column of cells, and each cell contains a Tile-stack object. If the horizontal property is true, the cells are arranged in a row, otherwise the cells are arranged in a column.
Properties:
containerId: a unique integer identifying a container of Tile objects.
defStack: the default Tile-stack object
count: the no. of cells (Tile-stack objects)
cells: a list of Tile-stack objects of length equal to the count property
dimensions: width, height (in pixels)
position: left, top (in pixels)
offset: distance in pixels between adjacent Tile-stack objects (width/height = offset multiplied by count)
horizontal: if true, the cells are arranged in a row, otherwise the cells are arranged in a column
visible: if false, Row-grid is not visible to user