code: public int put(Widget widget, String name) {
  		if (widget == null) return -1;
  		attach(widget);
  		for (int i = 0; i < content.length; ++i)
  			if (content[i] == null) {
  				content[i] = new Tab(widget, name);
  				this.sendElement();
  				return i;
  			}
  		throw new IndexOutOfBoundsException();
  		//return -1;
  	}
docs: Puts widget at first free index
  
  @param widget Widget to put
  @param name   Name of tab
  @return index of element in container