** a request to zoom in to a rectangle (APZCTreeManager::ZoomToRect())
=== Gecko === The In addition, the widget code provides APZ interacts with Gecko through an interface for interacting with Gecko, called '''[https://mxr.mozilla.org/mozilla-central/source/gfx/layers/ipc/GeckoContentController.h GeckoContentController]'''. The implementation of this interface is provided by the widget code, and as such is different for each platform. It may even be different for different APZCs within one platform (for example, in the B2G browser, APZCs representing scrollable elements in content processes use the RemoteContentController implementation, while those representing scrollable elements in the parent process will use a different implementation (currently being developed in {{bug|912657}})).
GeckoContentController allows the APZ to do the following:
