panelOpen static method
┌─ LABEL ──────────────────────────┐
Implementation
static void panelOpen(String label) {
final w = _w();
final tag = '─[ $label ]';
final rest = '─' * (w - tag.length - 2).clamp(0, 999);
print('\n$_cy┌$tag$rest┐$_r');
}