查找哪个 customtextbox 将消息发送到 customdatagridview

问：

我有一个customtextbox和一个customdatagridview。customtextbox 在其 OnKeyDown 事件上的行为为 Tab 键，在其后退键上的行为分别为 reverse Tab 键。现在在我的 customdatagridview 的 OnEnter 上，我想分析哪个 customtextbox 将焦点发送到 customdatagridview，以便我相应地更改我的当前单元格，但我对如何获取它感到困惑。

public partial class betterdatagridview : DataGridView
    {
    protected override void OnEnter(EventArgs e)
    {
        // datagridview has data 
        if (this.RowCount > 0)
        {

            if () // what to place here to check which customtextbox send me here 
            {
                this.CurrentCell = this.Rows[0].Cells[0]; // select the first cell in the first row
            }
            else if()
            {
                this.CurrentCell = this.Rows[RowCount - 1].Cells[0];//[0, this.RowCount - 1]; // select the last row's first cell
            }
         
            this.BeginEdit(true); // it must stay here 
            TextBox textBox = (TextBox)this.EditingControl; // Cast the EditingControl to TextBox
            textBox.SelectionStart = textBox.Text.Length; // select the textbox from last 
            
        }

下面是 customtextbox

  protected override void OnKeyDown(KeyEventArgs e)
    {
        if (!DisableFeatures)
        {
            if ((e.KeyCode == Keys.Enter || e.KeyCode == Keys.Down)&& this.Text !="")
            {
                e.Handled = true;
                e.SuppressKeyPress = true;
                TriggerEvent?.Invoke(Last, Name);
                if (!Last)
                {
                    SendKeys.Send("{TAB}");
                }
               
                return;
            }
            if ((e.KeyCode == Keys.Back || e.KeyCode == Keys.Up) && this.Text.Length == 0)
            {
                SendKeys.Send("+{TAB}");
            }
        }
        base.OnKeyDown(e);          
    }