private DockLayout pushDown() {
		DockLayout layout = new DockLayout();
		layout.mParent = this;
		for (int i = 0; i < mChildren.length; i++) {
			if (mChildren[i] instanceof DockLayout) {
				((DockLayout) mChildren[i]).mParent = layout;
			}
			layout.mChildren[i] = mChildren[i];
		}
		layout.mHorizontal = mHorizontal;
		layout.mDividerPosition = mDividerPosition;
		return layout;
	}