src/vs/base/browser/ui/toolbar/toolbar.ts/ToolBar/getItemsWidth
class ToolBar:	getItemsWidth(): number {
		let itemsWidth = 0;
		for (let i = 0; i < this.actionBar.length(); i++) {
			itemsWidth += this.actionBar.getWidth(i);
		}
		return itemsWidth;
	}