Defer Filtering Until the Filter Button is Clicked
By default, when in Popup filtering mode, filtering will be applied to the RadGridView control once any of the two field filter editors loses focus.
You can set a column's IsFilteringDeferred property to True to change this behavior so that filtering will be performed only when the end user clicks the Filter button. Please note that the Clear button will immediately clear the column filter regardless of this setting.
Example 1: Set the IsFilteringDeferred on all columns
private void GridView_Loaded(object sender, RoutedEventArgs e)
{
foreach (var column in this.GridView.Columns)
{
column.IsFilteringDeferred = true;
}
}