EditMode设为EditOnEnter

不过每次都要点击下来框的小三角才可以

添加如下函数，可以实现点击一次下拉：

private void dgvState_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            if (e.ColumnIndex >= 0 && e.RowIndex >= 0 && dgvState[e.ColumnIndex, e.RowIndex] != null && !dgvState[e.ColumnIndex, e.RowIndex].ReadOnly)
            {
                DataGridViewComboBoxColumn comboBoxColumn = dgvState.Columns[e.ColumnIndex] as DataGridViewComboBoxColumn;
                if (comboBoxColumn != null)
                {
                    this.dgvState.CurrentCell = dgvState[e.ColumnIndex, e.RowIndex];
                    dgvState.BeginEdit(true);
                    DataGridViewComboBoxEditingControl comboBoxEditingControl = dgvState.EditingControl as DataGridViewComboBoxEditingControl;
                    if (comboBoxEditingControl != null)
                    {
                        comboBoxEditingControl.DroppedDown = true;
                    }
                }
            }
        }

dgvState为datagridview的命名

本文参考网络文章，但很多文章都写自己是原创，我就随便找一个作为原文地址吧

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