// x = names and components interleaving.
// or just components.
// or just names.
// also, first element can be index of tab to open at start
// also, SUPER short demo syntax: jtabs(3)
static JTabbedPane jtabs(O... x) {
  int idx = 0;
  if (get(x, 0) instanceof Int) {
    idx = asInt(get(x, 0));
    x = dropFirst(x);
    if (empty(x)) {
      x = arrayrep(null, idx);
      idx = 0;
    }
  }
  new JTabbedPane tabs;
  int n = 0;
  for (int i = 0; i < l(x); i++) {
    ++n;
    if (x[i] instanceof Component)
      tabs.addTab("Tab " + n, wrap((Component) x[i]));
    else {
      S name = str(or(x[i], "Tab " + n));
      Component c;
      if (get(x, i+1) instanceof Component)
        c = (Component) get(x, ++i);
      else
        c = new JPanel;
      tabs.addTab(name, wrap(c));
    }
  }
  if (idx != 0)
    tabs.setSelectedIndex(max(tabs.getTabCount()-1, idx));
  ret tabs;
}

static JTabbedPane jtabs(Collection c) {
  ret jtabs(toObjectArray(c));
}