public partial class JournalForm : Form
    {
        private JournalConroller jcontroller = new JournalConroller();
        private int lastcolumn = 0;
        private int lastrow = 0;
        private Form f;

        public JournalForm()
        {
            InitializeComponent();
            edgvKeyJournal.CellMouseMove += new DataGridViewCellMouseEventHandler(edgvKeyJournal_CellMouseMove);
        }

        void edgvKeyJournal_CellMouseMove(object sender, DataGridViewCellMouseEventArgs e)
        {
            if ((sender as ExtDataGridView).Columns[e.ColumnIndex].Name == "Keys" && e.RowIndex >= 0)
            {
                if (e.RowIndex != lastrow || e.ColumnIndex != lastcolumn)
                {
                    //если курсор в нужном столбце и индексы столбцов изменились
                    if (f != null && f.Visible)
                    {
                        f.Close();
                        f.Dispose();
                    }
                    f = new EntranceProvForm(jcontroller.GetRowDetail(Convert.ToInt32((sender as ExtDataGridView).Rows[e.RowIndex].Cells["RowID"].Value)));
                    f.StartPosition = FormStartPosition.Manual;
                    f.Location = Cursor.Position;
                    f.FormBorderStyle = FormBorderStyle.None;
                    f.ShowInTaskbar = false;
                    f.Show();
                }
            }
            else
            {
                if (e.RowIndex != lastrow || e.ColumnIndex != lastcolumn)
                {
                    if (f != null && f.Visible)
                    {
                        f.Close();
                        f.Dispose();
                    }
                }
            }
            lastcolumn = e.ColumnIndex;
            lastrow = e.RowIndex;
        }
    }