How to prevent a backspace key stroke in a TextBox?

Question

I want to suppress a key stroke in a TextBox. To suppress all keystrokes other than Backspace, I use the following:

    private void KeyBox_KeyDown(object sender, System.Windows.Input.KeyEventArgs e)
    {
        e.Handled = true;
    }

However, I only want to suppress keystrokes when the key pressed was Backspace. I use the following:

        if (e.Key == System.Windows.Input.Key.Back)
        {
            e.Handled = true;
        }

However, this does not work. The character behind the selection start is still deleted. I do get "TRUE" in the output, so the Back key is being recognized. How would I prevent the user from pressing backspace? (My reason for this is that I want to delete words instead of characters in some cases, and so I need to handle the back key press myself).)

Answer 1

Just set e.SuppressKeyPress = true (in KeyDown event) when you want to suppress a keystroke. Ex, prevent backspace key change your text in textbox using the following code:

private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Back)
    {
        e.SuppressKeyPress = true;
    }
}

Note that if you try this in the txtBox1_KeyUp() handler, it will not appear to work (because KeyDown already handled the event for the TextBox).

Answer 2

In Silverlight, there is no way to handle system key events, such as backspace. Therefore, you can detect it, but not handle it manually.