src/vs/base/browser/ui/grid/gridview.ts/LeafNode/boundarySashes
class LeafNode:	set boundarySashes(boundarySashes: IRelativeBoundarySashes) {
		this._boundarySashes = boundarySashes;

		if (this.view.setBoundarySashes) {
			this.view.setBoundarySashes(toAbsoluteBoundarySashes(boundarySashes, this.orientation));
		}
	}