C#

Form2 F2 = new Form2();

SelectedGrammarID = Convert.ToInt32(SelectedRow.Cells["GrammarID"].Value);
this.Close();

using System;
public class IDEventArgs : EventArgs
{
    private int _ID;
    public IDEventArgs(int id)
    {
        _ID = id;
    }
    public int ID
    {
        get { return _ID; }
    }
}

public event EventHandler<IDEventArgs> GrammarIDSelected;
private void CompleteFormProcessing()
    {
        OnGrammarIDSelected(new IDEventArgs(
            Convert.ToInt32(SelectedRow.Cells["GrammarID"].Value)));
        Close();
    }
    protected virtual void OnGrammarIDSelected(IDEventArgs e)
    {
        EventHandler<IDEventArgs> eh = GrammarIDSelected;
        if (eh != null)
            eh(this, e);
    }

Form2 F2 = new Form2();
F2.GrammarIDSelected += new EventHandler<IDEventArgs>(F2_GrammarIDSelected);
F2.Show();

void F2_GrammarIDSelected(object sender, IDEventArgs e)
{
    // SelectedGrammarID in e.ID
}