src/vs/workbench/browser/parts/editor/noTabsTitleControl.ts/NoTabsTitleControl/updateEditorDirty
class NoTabsTitleControl:	updateEditorDirty(editor: EditorInput): void {
		this.ifEditorIsActive(editor, () => {
			const titleContainer = assertIsDefined(this.titleContainer);

			// Signal dirty (unless saving)
			if (editor.isDirty() && !editor.isSaving()) {
				titleContainer.classList.add('dirty');
			}

			// Otherwise, clear dirty
			else {
				titleContainer.classList.remove('dirty');
			}
		});
	}