Winform ComboBox独立绘制下拉选项的字体颜色

private void cb7_DrawItem(object sender, DrawItemEventArgs e) {     DrawCboItems(sender, e); }  private void cb7_SelectedIndexChanged(object sender, EventArgs e) {     SetCboTextColor(sender); }  private void SetCboTextColor(object sender) {     ComboBox cbx = sender as ComboBox;     if (cbx.Text == "+")         cbx.ForeColor = Color.Red;     else         cbx.ForeColor = Color.Black; }  private void DrawCboItems(object sender, DrawItemEventArgs e) {     ComboBox cbo = sender as ComboBox;      //初始化字体和背景色     Pen fColor = new Pen(Color.Black);     Pen bColor = new Pen(Color.White);      switch (e.Index)     {
　　　　 //下拉选项的索引     　　case 1:     　　{         　　fColor = new Pen(Color.Red);         　　break;     　　}     }      e.Graphics.FillRectangle(bColor.Brush, e.Bounds);     e.Graphics.DrawString((string)cbo.Items[e.Index], this.Font, fColor.Brush, e.Bounds); }