fires after applying a new style for a cell
| row | number | the ID of the row |
| column | number | the ID of the column |
| style | object | the new style for a cell |
| oldStyle | object | the old style of a cell |
| page | string | the name of the sheet |
$$("spsheet1").attachEvent("onStyleChange", function(row,column,style,oldStyle,page){
// some code here
});