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 |