src/vs/workbench/browser/parts/editor/editorPart.ts/EditorPart/doFindGroupByDirection
class EditorPart:	private doFindGroupByDirection(direction: GroupDirection, source: IEditorGroupView | GroupIdentifier, wrap?: boolean): IEditorGroupView {
		const sourceGroupView = this.assertGroupView(source);

		// Find neighbours and sort by our MRU list
		const neighbours = this.gridWidget.getNeighborViews(sourceGroupView, this.toGridViewDirection(direction), wrap);
		neighbours.sort(((n1, n2) => this.mostRecentActiveGroups.indexOf(n1.id) - this.mostRecentActiveGroups.indexOf(n2.id)));

		return neighbours[0];
	}