The area a cell in the column will be allocated, or %NULL
location to return x offset of a cell relative to @cell_area, or %NULL
location to return y offset of a cell relative to @cell_area, or %NULL
location to return width needed to render a cell, or %NULL
location to return height needed to render a cell, or %NULL
Obtains the width and height needed to render the column. This is used primarily by the #GtkTreeView.