code: public TabbedPanel put(Widget widget, String name, int index) {
  		if (index < 0 || index >= content.length) throw new IndexOutOfBoundsException();
  		if (widget == null) return this;
  		attach(widget);
  		content[index] = new Tab(widget, name);
  		this.sendElement();
  		return this;
  	}
docs: Puts new widget to the container
  
  @param widget Widget to put
  @param name   Name of tab
  @param index  id of 'cell' in the container to put widget to(numbered from 0)
  @return This instance for chaining