Hi, i had the same issue. It comes from the localization. If you set one, the override of the list does not work, and in code behind either because the load event is before the localization set the list. You actually need to set it in the prerendercomplete event, i did not try the prerender. So here :

private sub WebForm1_PrerenderComplete(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRenderComplete

WebHtmlEditor1.FontNameList.Clear()

WebHtmlEditor1.FontNameList.Add( "Times New Roman" )

end sub

Hi,

I tested codes within aspx and within aspx.cs and both worked as expected: drop-down font list showed custom values.
That is possible that somewhere in your logic of your application custom values are replaced, or removed, or similar. I suggest you to test/experiment with a stand alone webform, which has only editor. If it will work, then you may try to figure out why it fails in your actual application.

<ighedit:WebHtmlEditor ID="WebHtmlEditor1" runat="server" FontNameList="impact,arial black,Courier"></ighedit:WebHtmlEditor>
 

protected void Page_Load(object sender, EventArgs e)
{
  this.WebHtmlEditor1.FontNameList.Clear();
  this.WebHtmlEditor1.FontNameList.Add("impact");
  this.WebHtmlEditor1.FontNameList.Add("latha");
}