Please take it as question not a general discussion.

I have seen another similar thread in here which mentions same problem and ASPNET-187 raised for this.

ASPNET-187 was reported by Dimitris B in the following thread: WebCombo integrated with WebGrid on IE11.

If you are experiencing this issue when create WebCombo programmatically, set the ResultBoxWindowType of WebCombo's LayoutSettings to Normal should resolve the problem.

I modified Programmatic.aspx sample of WebCombo by adding a line of code in combo_InitializeLayout LayoutEventHandler and find that the reported problem is no longer persist.

protected void combo_InitializeLayout(object sender, LayoutEventArgs e)
{
    // Setup Behavior
    WebCombo combo = (WebCombo)sender;
    combo.DataTextField = "ContactName";
    combo.DataValueField = "CustomerID";
    combo.LayoutSettings.ResultBoxWindowType = DisplayType.Normal;
}

Please let me know if you have different result.

Great.....It woks...Thank Yudi

Thanks a lot...it helps me a lot.

Glad to know that set ResultBoxWindowType to Normal resolve the reported problem.

Should you need further assistance or run into any problems regarding our controls, feel free to post it into our forum. We would be happy to assist you again.