TextBox支持拖拽路径和文件

public class TextBoxPath : TextBox
{
    public TextBoxPath() : base()
    {
        this.AllowDrop = true;
        this.DoubleClick += TextBoxPath_DoubleClick;
        this.DragEnter += TextBoxPath_DragEnter;
        this.DragDrop += TextBoxPath_DragDrop;
    }

    private void TextBoxPath_DragEnter(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(DataFormats.FileDrop))
            e.Effect = DragDropEffects.Link;
        else
            e.Effect = DragDropEffects.None;
    }

    private void TextBoxPath_DragDrop(object sender, DragEventArgs e)
    {
        string path = ((System.Array)e.Data.GetData(DataFormats.FileDrop)).GetValue(0).ToString();
        (sender as Control).Text = path;
    }

    private void TextBoxPath_DoubleClick(object sender, EventArgs e)
    {
        FolderBrowserDialog dialog = new FolderBrowserDialog();
        if (dialog.ShowDialog() == DialogResult.OK)
        {
            (sender as Control).Text = dialog.SelectedPath;
        }
    }
}