Inserts child in the position after sibling in the list of children.
See [the migration guide](migrating-to-breakpoints.html#replace-adwleaflet)
If sibling is `NULL`, inserts child at the first position.
| this |
a leaflet |
| child |
the widget to insert |
| sibling |
the sibling after which to insert |
|
the [class@LeafletPage] for |