src/vs/base/browser/ui/grid/gridview.ts/GridView/constructor
class GridView:	constructor(options: IGridViewOptions = {}) {
		this.element = $('.monaco-grid-view');
		this.styles = options.styles || defaultStyles;
		this.proportionalLayout = typeof options.proportionalLayout !== 'undefined' ? !!options.proportionalLayout : true;

		this.firstLayoutController = new LayoutController(false);
		this.layoutController = new MultiplexLayoutController([
			this.firstLayoutController,
			...(options.layoutController ? [options.layoutController] : [])
		]);

		this.root = new BranchNode(Orientation.VERTICAL, this.layoutController, this.styles, this.proportionalLayout);
	}