The number of physical pixels on each side of the display rectangle into which the application can render, but which may be partially obscured by system UI (such as the system notification area), or or physical intrusions in the display (e.g. overscan regions on television screens or phone sensor housings).
Unlike Window.padding, this value does not change relative to Window.viewInsets. For example, on an iPhone X, it will not change in response to the soft keyboard being visible or hidden, whereas Window.padding will.
When this property changes, onMetricsChanged is called.
WindowPadding get viewPadding => _viewPadding;