In order to select objects by drawing a line it's necessary to set these parameters:
Query: External Layer ID of the WebOffice 10 R3 query layer.
Return Key: Specifies the field to be returned in the response (it is possible to use more return keys separated by semicolon ';').
Callback Function: Specifies a call back function.
Note: The callback in the WebOffice map widget test container opens an alert with the return key of the selected object.

WebOffice map widget test container - Select Line Tool