DataGridViewComboBoxColumn单击下拉功能

1.设置DataGridView控件的EditMode属性为EditOnEnter

如：DataGridView1.EditMode = System.Windows.Forms.DataGridViewEditMode.EditOnEnter

2.添加DataGridView的CellClick事件，逻辑如下：

private void dgvColumnMap_CellClick(object sender, DataGridViewCellEventArgs e)

        {

            if (e.ColumnIndex >= 0 && e.RowIndex >= 0 && dgvColumnMap[e.ColumnIndex, e.RowIndex] != null && !dgvColumnMap[e.ColumnIndex, e.RowIndex].ReadOnly)

            {

                DataGridViewComboBoxColumn comboBoxColumn = dgvColumnMap.Columns[e.ColumnIndex] as DataGridViewComboBoxColumn;

                if (comboBoxColumn != null)

                {

                    dgvColumnMap.BeginEdit(true);

                    DataGridViewComboBoxEditingControl comboBoxEditingControl = dgvColumnMap.EditingControl as DataGridViewComboBoxEditingControl;

                    if (comboBoxEditingControl != null)

                    {

                        comboBoxEditingControl.DroppedDown = true;

                    }

                }

            }

        }