Serialize the implied tree of layers and handlers into a list
that can be traversed from the end to collect handlers.
This change will make it easier to switch op representation in
a follow-up change.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
With an interface instead of anonymous functions, amending an
area's parameters can be done even after adding it to an OpHandler.
This will be useful when we switch to serialized op lists.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
gioui.org/ui was renamed from gioui.org/ui/ui before the release,
but the import order wasn't changed accordingly.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Elias Naur