I'm a content pane, and I'm the first child of the SplitContainer, so I appear on the left.
My initial size is 20%, but if you adjust it and come back to the demo,
my parent (the SplitContainer) will remember the size you set.
On my right is a split container. (The parent split container contains a child split container.)
This is the top part of the inner split container.
...and this is the bottom.
I'm another content pane, on the right.