退格只能使用一次？

Question

I've got a custom TextBox-like control. I'm trying to handle backspaces with this:

    private void PerformBackspace() {
        System.Diagnostics.Debug.WriteLine("Got a backspace. Text is currently \"{0}\".", (object)this.Text);
        string newText = this.Text.Substring(0, this.Text.Length - 1);
        System.Diagnostics.Debug.WriteLine("Changing text to \"{0}\".", (object)newText);
        this.Text = newText;
        System.Diagnostics.Debug.WriteLine("Text is now \"{0}\".", (object)this.Text);
    }

In OnKeyDown I call this method, and it works, but only for one character. Backspacing twice in a row does not work, you have to type at least one character between backspaces for some reason. Now is Substring just not working??? This is the output I get when I backspace twice:

Got a backspace. Text is currently "My textbox.".
Changing text to "My textbox".
Text is now "My textbox".
Got a backspace. Text is currently "My textbox".
Changing text to "My textbox".
Text is now "My textbox".

This is quite possibly the strangest issue I have ever seen.

Answer 1

Try calling it from the OnKeyUp() event.

Answer 2

As it turns out, the '\b' character was getting appended to my text after pressing the backspace key.