Private Sub RadialMenu_ItemClick(sender As Object, e As RadialMenuItemClickEventArgs)
    Select Case TryCast(e.RadialMenuItem.UserData, String)
        Case "check"
            e.RadialMenuItem.Checked = Not e.RadialMenuItem.Checked
            e.RadialMenuItem.Text = If(e.RadialMenuItem.Checked, "ON", "OFF")
            e.RadialMenuItem.ToolTip = If(e.RadialMenuItem.Checked, "Checked item", "Unchecked item")
            e.RadialMenuItem.Image = If(e.RadialMenuItem.Checked, Global.RadialMenuTest.Properties.Resources.bullet_ball_glass_red, Global.RadialMenuTest.Properties.Resources.bullet_ball_glass_grey)
            Exit Select
        Case "locale"
            Dim parent As RadialMenuItem = TryCast(e.RadialMenuItem.Parent, RadialMenuItem)
            If parent IsNot Nothing Then
                For Each it As RadialMenuItem In parent.Items
                    If DirectCast(it.UserData, String) = "locale" Then
                        it.Checked = False
                    End If
                Next
            End If
            e.RadialMenuItem.Checked = True
            Exit Select
    End Select
End Sub

private void RadialMenu_ItemClick(object sender, RadialMenuItemClickEventArgs e)
        {
            switch (e.RadialMenuItem.UserData as string)
            {
                case "check":
                    e.RadialMenuItem.Checked = !e.RadialMenuItem.Checked;
                    e.RadialMenuItem.Text = e.RadialMenuItem.Checked ? "ON" : "OFF";
                    e.RadialMenuItem.ToolTip = e.RadialMenuItem.Checked ? "Checked item" : "Unchecked item";
                    e.RadialMenuItem.Image = e.RadialMenuItem.Checked ?
                        global::RadialMenuTest.Properties.Resources.bullet_ball_glass_red :
                        global::RadialMenuTest.Properties.Resources.bullet_ball_glass_grey;
                    break;
                case "locale":
                    RadialMenuItem parent = e.RadialMenuItem.Parent as RadialMenuItem;
                    if (parent != null)
                    {
                        foreach (RadialMenuItem it in parent.Items)
                            if ((string)it.UserData == "locale")
                                it.Checked = false;
                    }
                    e.RadialMenuItem.Checked = true;
                    break;
            }
        }