/// <summary>
/// Sets the handler for printing error messages.
/// </summary>
/// <param name="handler">the new error message handler</param>
/// <returns>the old error message handler</returns>
public static PrintFunc SetPrintErrorHandler(PrintFunc handler)
{
var helper = new PrintHelper(handler);
var prev = GLib.GSetPrinterrHandler(helper.Handler);
helper = new PrintHelper(prev);
return(helper.Invoker);
}