adds a select area
| start | object | the id object of the left top cell, contains two properties: the row id and the column id | 
| end | object | the id object of the right cell, contains two properties: the row id and the column id | 
| preserve | boolean | defines if the previous select area should be saved, false by default | 
| area_name | string | optional, the name used to address to an area to change or to delete it | 
| css | string | optional, the css style for an area | 
| handle | boolean | optional, defines whether selection will be resized with or without a handle | 
Available only in PRO Edition
$$("dtable").addSelectArea(start,end,preserve);