Select All shortcut fails when MultiLine property is True

Question

I have a Windows forms application that has a standard TextBox on it. There are no events being handled and no menus on the form. When I press the Ctrl+A shortcut to select all the text, I get a ding, and nothing is selected.

To confirm I didn't inadvertently code something I created a new Windows forms application with only a textbox on the form. I tried it with both C# and VB.Net and it is the same in both. I have tried this in Visual Studio 2012 Update 1 running on Windows 7, and Visual Studio 2008 running on Windows XP and it behaves the same in each instance.

I can catch the key stroke combination in the KeyDown event easily enough, but even after setting e.Cancel = true the machine stills sounds the "ding".

Is there a way to suppress the sound, or even better, a way to make the textbox accept the shortcut the same way a non-multiline textbox does?

Answer 1

This is a surprise to many programmers but the native Windows edit control doesn't actually implement Ctrl+A as a shortcut when it is in multi-line mode. It has to be implemented by the program that uses it. You can see this for example in Notepad, a program that uses a multi-line edit control. Use File + Open + File, select c:\windows\notepad.exe, open the Accelerator node and double-click one of the tables.

Implementing it is not difficult:

    private void textBox1_KeyDown(object sender, KeyEventArgs e) {
        if (e.KeyData == (Keys.Control | Keys.A)) {
            textBox1.SelectAll();
            e.Handled = e.SuppressKeyPress = true;
        }
    }

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UPDATE: changed in .NET 4.6.1, System.Windows.Forms.TextBox now implements Ctrl+A for multi-line textboxes as well.