src/vs/workbench/browser/parts/titlebar/titlebarPart.ts/TitlebarPart/onActiveEditorChange
class TitlebarPart:	private onActiveEditorChange(): void {

		// Dispose old listeners
		this.activeEditorListeners.clear();

		// Calculate New Window Title
		this.titleUpdater.schedule();

		// Apply listener for dirty and label changes
		const activeEditor = this.editorService.activeEditor;
		if (activeEditor) {
			this.activeEditorListeners.add(activeEditor.onDidChangeDirty(() => this.titleUpdater.schedule()));
			this.activeEditorListeners.add(activeEditor.onDidChangeLabel(() => this.titleUpdater.schedule()));
		}
	}