Causes the minimum and/or natural width to grow if the new proposed sizes exceed the current minimum and natural width.
This is used by `GtkCellAreaContext` implementations during the request process over a series of `GtkTreeModel` rows to progressively push the requested width over a series of get_preferred_width requests.
| this |
a `GtkCellAreaContext` |
| minimum_width |
the proposed new minimum width for this |
| natural_width |
the proposed new natural width for this |