src/vs/workbench/contrib/notebook/browser/contrib/find/notebookFindReplaceWidget.ts/NotebookFindInput/updateFilterState
class NotebookFindInput:	updateFilterState(changed: boolean) {
		this._filterChecked = changed;
		if (this.regex) {
			if (this._filterChecked) {
				this.regex.disable();
				this.regex.domNode.tabIndex = -1;
				this.regex.domNode.classList.toggle('disabled', true);
			} else {
				this.regex.enable();
				this.regex.domNode.tabIndex = 0;
				this.regex.domNode.classList.toggle('disabled', false);
			}
		}
		this.applyStyles();
	}