Passing an *Awaitable* Anonymous Function as a Parameter

private async void UpdateButton(Func<Task<bool>> post)
{
    if (!await post())
        ErrorBox.Text = "Error posting message.";
}

–EDIT–

UpdateButton(()=>Post("ss"));

private async void UpdateButton(Func<Task<bool>> post)
{
    if (!await post())
        this.Text = "Error posting message.";
}

public virtual async Task<bool> Post(string messageId)
{
    return await Task.Factory.StartNew(() => true);
}