To reproduce:
public Form1()
{
InitializeComponent();
BindingList<Item> items = new BindingList<Item>();
for (int i = 0; i < 30; i++)
{
if (i % 3 == 0)
{
items.Add(new Item(i,"Item" + i, IndeterminateBoolean.YesAndNo));
}
else if (i % 3 == 1)
{
items.Add(new Item(i, "Item" + i, IndeterminateBoolean.Yes));
}
else
{
items.Add(new Item(i, "Item" + i, IndeterminateBoolean.No));
}
}
this.radGridView1.DataSource = items;
this.radGridView1.AutoSizeColumnsMode = GridViewAutoSizeColumnsMode.Fill;
this.radGridView1.EnableFiltering = true;
this.radGridView1.ShowHeaderCellButtons = true;
this.radGridView1.ShowFilteringRow = false;
}
public class Item
{
public int Id { get; set; }
public string Name { get; set; }
public IndeterminateBoolean IsActive { get; set; }
public Item(int id, string name, IndeterminateBoolean isActive)
{
this.Id = id;
this.Name = name;
this.IsActive = isActive;
}
}
public enum IndeterminateBoolean
{
No,
Yes,
YesAndNo
}
Workaround: use custom filtering http://docs.telerik.com/devtools/winforms/gridview/filtering/custom-filtering