The split container is a container with a movable split and the option for 2 or 3 elements.
import toga
split = toga.SplitContainer()
left_container = toga.Box()
right_container = toga.ScrollContainer()
split.content = [left_container, right_container]
Split direction is set on instantiation using the direction keyword argument. Direction is vertical by default.
import toga
split = toga.SplitContainer()
left_container = toga.Box()
right_container = toga.ScrollContainer(direction=toga.ScrollContainer.HORIZONTAL)
split.content = [left_container, right_container]
toga.interface.widgets.splitcontainer.SplitContainer