Hello Jiri,

Thank you for sending the feature suggestion - indeed, for the time being there isn't a direct way to find out when the popup with the suggestions is shown/hidden.

I would suggest the following approach as a temporary workaround - you can access the popup through a reflection and subscribe to its PropertyChanged event to track when IsOpen is updated:

FieldInfo internalPopup = this.autoComplete.GetType().GetField("popup", BindingFlags.NonPublic | BindingFlags.Instance);
RadPopup myPopup = internalPopup.GetValue(this.autoComplete) as RadPopup;
myPopup.PropertyChanged += (sender, args) =>
{
    if (args.PropertyName == "IsOpen")
    {
        bool isOpen = (sender as RadPopup).IsOpen;
    }
};

Regards,
Yana
Progress Telerik