selects all items or the specified range
| from | string | the id of an item that selection will be started from | 
| to | string | the id of an item that selection will be ended with | 
webix.ui({
    view:"dataview",
    id:"data",
    ...
});
$$('data').selectAll(); //selects all items in dataview
If the parameters aren't specified, all items will be selected.