src/vs/workbench/browser/parts/compositeBar.ts/CompositeBarModel/add
class CompositeBarModel:	add(id: string, name: string, order: number | undefined, requestedIndex: number | undefined): boolean {
		const item = this.findItem(id);
		if (item) {
			let changed = false;
			item.name = name;
			if (!isUndefinedOrNull(order)) {
				changed = item.order !== order;
				item.order = order;
			}
			if (!item.visible) {
				item.visible = true;
				changed = true;
			}

			return changed;
		} else {
			const item = this.createCompositeBarItem(id, name, order, true, true, true);
			if (!isUndefinedOrNull(requestedIndex)) {
				let index = 0;
				let rIndex = requestedIndex;
				while (rIndex > 0 && index < this.items.length) {
					if (this.items[index++].visible) {
						rIndex--;
					}
				}

				this.items.splice(index, 0, item);
			} else if (isUndefinedOrNull(order)) {
				this.items.push(item);
			} else {
				let index = 0;
				while (index < this.items.length && typeof this.items[index].order === 'number' && this.items[index].order! < order) {
					index++;
				}
				this.items.splice(index, 0, item);
			}

			return true;
		}
	}