I would like to know if its possible to activate filter in a grid any time.
I currently have a grid with alot of data in it but sometimes i need to be able to filter on empty value so i can modify only the row who doesn't have data in it.
The filter options "IsNull" and "NotIsNull" filter by empty values, or values that are null in your data source. Note that if you may need to set EnableLinqExpressions="false" for these options to work.
Alternatively, you can implement your custom filtering, for example with RadComboBox containing an item that filters by null vlaues. Attached is a small web page that demonstrates this.