How to reproduce: check the attached project and video Workaround: public partial class RadForm1 : Telerik.WinControls.UI.RadForm { public RadForm1() { InitializeComponent(); this.LostFocus += RadForm1_LostFocus1; } private void RadForm1_LostFocus1(object sender, EventArgs e) { //Workaround this.radMenu1.GetType().GetField("shouldShowChildren", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic).SetValue(this.radMenu1, false); } }