src/vs/workbench/contrib/files/browser/views/openEditorsView.ts/OpenEditorsView/elementCount
class OpenEditorsView:	private get elementCount(): number {
		return this.editorGroupService.groups.map(g => g.count)
			.reduce((first, second) => first + second, this.showGroups ? this.editorGroupService.groups.length : 0);
	}