Question

How can I capture a tab entered in a Silverlight TextBox and render 4 spaces (or a tab) in it’s place?

I can’t figure out how to block the tab navigation.

Answer 1

Here is what I do (similar to Johannes’ code):

        private const string Tab = "    ";
    void textBox_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Tab)
        {
            int selectionStart = textBox.SelectionStart;
            textBox.Text = String.Format("{0}{1}{2}", 
                textBox.Text.Substring(0, textBox.SelectionStart),
                Tab,
                textBox.Text.Substring(textBox.SelectionStart + textBox.SelectionLength, (textBox.Text.Length) - (textBox.SelectionStart + textBox.SelectionLength))
                );
            e.Handled = true;
            textBox.SelectionStart = selectionStart + Tab.Length;
        }
    }

This behaves just how you expect even if you select some text and hit the ol’ “Tab” key.

One more thing: I tried having the tab string as “\t”, but to no avail. The tab rendered, but was the width of a single space – hence the value for the Tab const being four spaces.