Forcing a user control in a datagridviewcell to be displayed over other cells?

Hi there everyone,

I have been searching for a long time and cannot seem to find the answer i am looking for;

What I want is a a complex user control to be inserted into each cell.

What I have done is follow these posts, except now just use a custom control instead of the datetimepicker.

However the custom control is only being displayed in the cell and will not overlap.

Some googling has shown that the best method of resolving this issue is making the user control from the base class of dropdownlist.

Any help will greatly be appreciated.

This is what I have so far: (which is basically https://msdn.microsoft.com/en-us/library/7tas5c80(v=vs.110).aspx)

public class ItemListBoxCell : DataGridViewTextBoxCell
{

    public ItemListBoxCell()
        : base()
    {
        // Use the short date format.
        // this.Style.Format = "d";

    }

    public override void InitializeEditingControl(int rowIndex, object
        initialFormattedValue, DataGridViewCellStyle dataGridViewCellStyle)
    {
        // Set the value of the editing control to the current cell value.
        base.InitializeEditingControl(rowIndex, initialFormattedValue,
            dataGridViewCellStyle);

        ItemListBoxEditingControl ctl = DataGridView.EditingControl as ItemListBoxEditingControl;
    }

    public override Type EditType
    {
        get
        {
            // Return the type of the editing control that CalendarCell uses.
            return typeof(ItemListBoxEditingControl);
        }
    }

    public override Type ValueType
    {
        get
        {
            // Return the type of the value that CalendarCell contains.

            return typeof(string);
        }
    }

    public override object DefaultNewRowValue
    {
        get
        {
            // Use the current date and time as the default value.
            //return DateTime.Now;
            return "";
        }
    }
}

class ItemListBoxEditingControl : TestControl, IDataGridViewEditingControl
{
    DataGridView dataGridView;
    private bool valueChanged = false;
    int rowIndex;

    public ItemListBoxEditingControl()
    {
        //this.Format = DateTimePickerFormat.Short;
    }

    // Implements the IDataGridViewEditingControl.EditingControlFormattedValue
    // property.
    public object EditingControlFormattedValue
    {
        get
        {
            //return this.Value.ToShortDateString();
            // return this.SelectedText.ToString();
            return this.ToString();
        }
        set
        {
            if (value is String)
            {
                try
                {
                    // This will throw an exception of the string is
                    // null, empty, or not in the format of a date.
                    // this.Value = DateTime.Parse((String)value);
                }
                catch
                {
                    // In the case of an exception, just use the
                    // default value so we're not left with a null
                    // value.
                    //this.Value = DateTime.Now;
                }
            }
        }
    }

    // Implements the
    // IDataGridViewEditingControl.GetEditingControlFormattedValue method.
    public object GetEditingControlFormattedValue(
        DataGridViewDataErrorContexts context)
    {
        return EditingControlFormattedValue;
    }

    // Implements the
    // IDataGridViewEditingControl.ApplyCellStyleToEditingControl method.
    public void ApplyCellStyleToEditingControl(
        DataGridViewCellStyle dataGridViewCellStyle)
    {
        this.Font = dataGridViewCellStyle.Font;
        //this.CalendarForeColor = dataGridViewCellStyle.ForeColor;
        //this.CalendarMonthBackground = dataGridViewCellStyle.BackColor;
    }

    // Implements the IDataGridViewEditingControl.EditingControlRowIndex
    // property.
    public int EditingControlRowIndex
    {
        get
        {
            return rowIndex;
        }
        set
        {
            rowIndex = value;
        }
    }

    // Implements the IDataGridViewEditingControl.EditingControlWantsInputKey
    // method.
    public bool EditingControlWantsInputKey(
        Keys key, bool dataGridViewWantsInputKey)
    {
        // Let the DateTimePicker handle the keys listed.
        switch (key & Keys.KeyCode)
        {
            case Keys.Left:
            case Keys.Up:
            case Keys.Down:
            case Keys.Right:
            case Keys.Home:
            case Keys.End:
            case Keys.PageDown:
            case Keys.PageUp:
                return true;
            default:
                return !dataGridViewWantsInputKey;
        }
    }

    // Implements the IDataGridViewEditingControl.PrepareEditingControlForEdit
    // method.
    public void PrepareEditingControlForEdit(bool selectAll)
    {
        // No preparation needs to be done.
    }

    // Implements the IDataGridViewEditingControl
    // .RepositionEditingControlOnValueChange property.
    public bool RepositionEditingControlOnValueChange
    {
        get
        {
            return false;
        }
    }

    // Implements the IDataGridViewEditingControl
    // .EditingControlDataGridView property.
    public DataGridView EditingControlDataGridView
    {
        get
        {
            return dataGridView;
        }
        set
        {
            dataGridView = value;
        }
    }

    // Implements the IDataGridViewEditingControl
    // .EditingControlValueChanged property.
    public bool EditingControlValueChanged
    {
        get
        {
            return valueChanged;
        }
        set
        {
            valueChanged = value;
        }
    }

    // Implements the IDataGridViewEditingControl
    // .EditingPanelCursor property.
    public Cursor EditingPanelCursor
    {
        get
        {
            return base.Cursor;
        }
    }

   /* protected override void OnSelectedValueChanged(EventArgs eventargs)
    {
        // Notify the DataGridView that the contents of the cell
        // have changed.
        valueChanged = true;
        base.OnSelectedValueChanged(eventargs);
        this.EditingControlDataGridView.NotifyCurrentCellDirty(true);
        //base.OnValueChanged(eventargs);
    }*/
}

and then the custom control with a simple button, for testing.

 private void buttonclick(object sender, EventArgs e)
        {
            MessageBox.Show("test");
        }

how I apply this usercontrol to the datagridview is by doing a db query, binding the data and then changing the columns like this

 DataGridViewCell listboxcell = new ItemListBoxCell();

ItemDatagridView.Columns[2].CellTemplate = listboxcell;

Also this is very new to me.. So please go easy on me..