C#

clsUsage _clsUsage = new clsUsage();<br />
_clsUsage.CalcUsage();<br />

frmStatus _frmStatus = new frmStatus();<br />
_frmStatus.Show();<br />
//doing some operations and modifying attributes to controls of frmStatus form<br />
_frmStatus.Close();

//created a property in action class<br />
private Form parentForm;<br />
<br />
public Form ParentForm<br />
{<br />
   get { return parentForm; }<br />
   set { parentForm = value; }<br />
}<br />
<br />
//in frmMain in clicked event added<br />
_clsUsage.ParentForm = this;<br />
<br />
//in the action class in the action method<br />
_frmStatus.Parent = ParentForm;

private void dgcboDocNo_SelectedIndexChanged(object sender, EventArgs e)
{
    System.Diagnostics.Debug.WriteLine(dataGridView1.CurrentCell.ColumnIndex + "SelectedIndexChanged");

    string docno = ((DataGridViewComboBoxEditingControl)sender).Text.ToString();
    DataRow[] dr = myDs.Tables["DetailDocRegister"].Select("DocNo = '" + docno + "'");
    if (dr.Length > 0)  // <======================= TEST HERE ======================================================
    {
        int y = dataGridView1.CurrentCellAddress.Y;
        dataGridView1.Rows[y].Cells[1].Value = dr[0]["DocTitle"];
    }
}

private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
    DataGridViewComboBoxEditingControl combo = e.Control as DataGridViewComboBoxEditingControl;  // <=============== HERE ================
    System.Diagnostics.Debug.WriteLine(dataGridView1.CurrentCell.ColumnIndex + "EditControlShowing");
    if (combo != null)
    {
        combo.SelectedIndexChanged -= new EventHandler(dgcboDocNo_SelectedIndexChanged);
        combo.SelectedIndexChanged += new EventHandler(dgcboDocNo_SelectedIndexChanged);
    }
}

public static void CopyDirectory(string source, string destination, bool overwrite)
       {
           // Create the destination folder if missing.
           if (!Directory.Exists(destination))
               Directory.CreateDirectory(destination);

           DirectoryInfo dirInfo = new DirectoryInfo(source);

           // Copy all files.
           foreach (FileInfo fileInfo in dirInfo.GetFiles())
               fileInfo.CopyTo(Path.Combine(destination, fileInfo.Name), overwrite);

           // Recursively copy all sub-directories.
           foreach (DirectoryInfo subDirectoryInfo in dirInfo.GetDirectories())
               CopyDirectory(subDirectoryInfo.FullName, Path.Combine(destination, subDirectoryInfo.Name), overwrite);
       }