src/vs/workbench/browser/parts/editor/editorPart.ts/EditorPart/fillGridNodes
class EditorPart:	private fillGridNodes(target: IEditorGroupView[], node: GridBranchNode<IEditorGroupView> | GridNode<IEditorGroupView>): void {
		if (isGridBranchNode(node)) {
			node.children.forEach(child => this.fillGridNodes(target, child));
		} else {
			target.push(node.view);
		}
	}