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Gets or sets a function that gets the HTML in the control header.
[JsonConverter(typeof(FunctionConverter))]
public string HeaderFormatter { get; set; }
<JsonConverter(GetType(FunctionConverter))>
Public Property HeaderFormatter As String
By default, the control header content is determined based on the Placeholder, MaxHeaderItems, and on the current selection. You may customize the header content by specifying a function that returns a custom string based on whatever criteria your application requires.