SMART datagrid v.1 > Classes > TreeOptions
Callback function which returns icon index which will be displayed in Tree Row.
First, if TreeRow.iconIndex is not undefined, the icon of tree row will use the corresponding value. If iconIndex is undefined and set iconCallback, it will use the value returned by iconCallback. Lastly, if it has not specify iconCallback, it will use the value of field which has been specified by iconField.
Defaults to null.