C＃winforms datagridview - 上下文菜单出现在第二次右键单击，而不是第一次

Question

当用户右键单击某行时，我已在DataGridView控件的cellmousedown事件中将上下文菜单设置为apear。 打开包含网格的表单后，我必须在一行上单击2次，以便将上下文菜单设置为apear。在“第一次打开”之后，上下文菜单表现正常 - ＆gt;只需单击一下即可显示我关注的控件。 我猜网格属性/方法有一个错误的设置，但是哪一个？

以下是网格格式的代码：

        /* format grid */
        // Initialize basic DataGridView properties.
        dgv.BackgroundColor = Color.LightGray;
        dgv.BorderStyle = BorderStyle.FixedSingle;
        // Set property values appropriate for read-only display and limited interactivity. 
        dgv.AllowUserToAddRows = false;
        dgv.AllowUserToDeleteRows = false;
        dgv.AllowUserToOrderColumns = true;
        dgv.ReadOnly = true;
        dgv.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
        dgv.MultiSelect = false;
        dgv.AutoSizeRowsMode = DataGridViewAutoSizeRowsMode.None;
        dgv.AllowUserToResizeColumns = false;
        dgv.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.DisableResizing;
        dgv.AllowUserToResizeRows = false;
        dgv.RowHeadersVisible = false;

        dgv.RowsDefaultCellStyle.BackColor = Color.White;
        dgv.AlternatingRowsDefaultCellStyle.BackColor = Color.LightGoldenrodYellow;

        // Set the row and column header styles.
        dgv.ColumnHeadersDefaultCellStyle.ForeColor = Color.Black;
        dgv.ColumnHeadersDefaultCellStyle.BackColor = Color.White;

        dgv.RowTemplate.MinimumHeight = 38;
        dgv.DefaultCellStyle.WrapMode = DataGridViewTriState.True;

        DataGridViewCellStyle hStyle = new DataGridViewCellStyle();
        hStyle.Font = new Font("Arial", 9, FontStyle.Bold);
        dgv.ColumnHeadersDefaultCellStyle = hStyle;

        DataGridViewCellStyle cellStyle = new DataGridViewCellStyle();
        cellStyle.Font = new Font("Arial", 8, FontStyle.Regular);
        cellStyle.Alignment = DataGridViewContentAlignment.MiddleLeft;

这是启动上下文菜单的代码：

    private void dgv_CellMouseDown(object sender, DataGridViewCellMouseEventArgs e)
    {
        // Ignore if a column or row header is clicked
        if (e.RowIndex != -1 && e.ColumnIndex != -1)
        {
            if (e.Button == MouseButtons.Right)
            {
                DataGridViewCell clickedCell = (sender as DataGridView).Rows[e.RowIndex].Cells[e.ColumnIndex];

                // Here you can do whatever you want with the cell
                dgv.CurrentCell = clickedCell;  // Select the clicked cell, for instance

                // Get mouse position relative to the vehicles grid
                var relativeMousePosition = dgv.PointToClient(Cursor.Position);

                // Show the context menu
                mnuOferta.Show(dgv, relativeMousePosition);
            }
        }

谢谢！