code: function updateAlignButton( align ) {
          var aligns = $G( "videoFloat" ).children;
          for ( var i = 0, ci; ci = aligns[i++]; ) {
              if ( ci.getAttribute( "name" ) == align ) {
                  if ( ci.className !="focus" ) {
                      ci.className = "focus";
                  }
              } else {
                  if ( ci.className =="focus" ) {
                      ci.className = "";
                  }
              }
          }
      }
docs: 依据传入的align值更新按钮信息
  @param align