src/vs/workbench/contrib/markers/browser/markersView.ts/MarkersView/computeFilterStats
class MarkersView:	private computeFilterStats(): { total: number; filtered: number; } {
		let filtered = 0;
		if (this.tree) {
			const root = this.tree.getNode();

			for (const resourceMarkerNode of root.children) {
				for (const markerNode of resourceMarkerNode.children) {
					if (resourceMarkerNode.visible && markerNode.visible) {
						filtered++;
					}
				}
			}
		}

		return { total: this.markersModel.total, filtered };
	}