Easiest way to create a custom dialog box which returns a value?
public static class Prompt
    {
        public static int ShowDialog(string text, string caption)
        {
            Form prompt = new Form();
            prompt.Width = 500;
            prompt.Height = 100;
            prompt.Text = caption;
            Label textLabel = new Label() { Left = 50, Top=20, Text=text };
            NumericUpDown inputBox = new NumericUpDown () { Left = 50, Top=50, Width=400 };
            Button confirmation = new Button() { Text = "Ok", Left=350, Width=100, Top=70 };
            confirmation.Click += (sender, e) => { prompt.Close(); };
            prompt.Controls.Add(confirmation);
            prompt.Controls.Add(textLabel);
            prompt.Controls.Add(inputBox);
            prompt.ShowDialog();
            return (int)inputBox.Value;
        }
    }

int promptValue = Prompt.ShowDialog("Test", "123");