c# winforms events restore textbox contents on escape

Question

Using c# in 2008 Express. I have a textbox containing a path. I append a "\" at the end on Leave Event. If the user presses 'Escape' key I want the old contents to be restored. When I type over all the text and press 'Escape' I hear a thump and the old text isn't restored. Here what I have so far ...

    public string _path;
    public string _oldPath;

        this.txtPath.KeyPress += new System.Windows.Forms.KeyPressEventHandler(txtPath_CheckKeys);
        this.txtPath.Enter +=new EventHandler(txtPath_Enter);
        this.txtPath.LostFocus += new EventHandler(txtPath_LostFocus);

    public void txtPath_CheckKeys(object sender, KeyPressEventArgs kpe)
    {           if (kpe.KeyChar == (char)27)
        {
            _path = _oldPath;
        }
    }

    public void txtPath_Enter(object sender, EventArgs e)
    {
        //AppendSlash(sender, e);
        _oldPath = _path;
    }
    void txtPath_LostFocus(object sender, EventArgs e)
    {
        //throw new NotImplementedException();
        AppendSlash(sender, e);
    }
    public void AppendSlash(object sender, EventArgs e) 
    {
        //add a slash to the end of the txtPath string on ANY change except a restore
        this.txtPath.Text += @"\";
    }

Thanks in advance,

Answer 1

Your txtPath_CheckKeys function assigns the path to the old path, but never actually updates the Text in the TextBox. I suggest changing it to this:

public void txtPath_CheckKeys(object sender, KeyPressEventArgs kpe)
{
    if (kpe.KeyCode == Keys.Escape)
    {
        _path = _oldPath;
        this.txtPath.Text = _path;
    }
}

Answer 2

The Control.Validating event might help you.

It describes the order in which events are triggered. So, choosing the event that best suits your need will make it easier to implement this feature.

It might be too much for the need, but trying to Invalidate the control might help too.

Let me know whether it helps.