C#

if (e.KeyCode == Keys.Enter && (sender as TextEdit).Text.Trim() != "")
{
    this.Cursor = Cursors.WaitCursor;

    is_form_exists = false;

    foreach (Form search_resul_form in this.MdiChildren)
    {
        frmSearchResult search_form = search_resul_form as frmSearchResult;

        if ((string)search_form.Tag == "BROWSE_PATIENTS")
        {
            // search_form.Activated(null, null);
            search_form.find_what = "FILE";
            search_form.find_text1 = (sender as TextEdit).Text.Trim();
            search_form.find_text2 = null;
            search_form.browse_result();
            search_form.Activate();
            is_form_exists = true;
            break;
        }
    }

    if (is_form_exists == false)
    {
        frmSearchResult SearchResultForm = new frmSearchResult(public_var);
        SearchResultForm.Tag = "BROWSE_PATIENTS";
        SearchResultForm.MdiParent = this;
        SearchResultForm.Dock = DockStyle.Fill;
        SearchResultForm.find_what = "FILE";
        SearchResultForm.find_text1 = (sender as TextEdit).Text.Trim();
        SearchResultForm.find_text2 = null;
        SearchResultForm.Show();
    }

    (sender as TextEdit).Text = "";

    this.Cursor = Cursors.Default;
}