If EnableVisualStyles is not set on project it does not work (CTRL+A). I added this:

Application.EnableVisualStyles()

Hope this helps! 

On UltraTextEditor's event OnKeyDown you can write this:

        private void Note_TextEditor_KeyDown(object sender, KeyEventArgs e)

        {

            if (e.KeyCode == Keys.A && e.Modifiers == Keys.Control)

                this.Note_TextEditor.SelectAll();

        }

I noticed the same problem with the windows TextBox control. Apparently, they do not support CTRL-A.

Here is some VB code to add the functionality:

http://vb-helper.com/howto_net_handle_ctrl_a.html

Private Sub TextBox2_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles _
    TextBox2.KeyPress
    If e.KeyChar = Convert.ToChar(1) Then
        DirectCast(sender, TextBox).SelectAll()
        e.Handled = True
    End If
End Sub

Hi,

I just tested this out by placing a new UltraTextEditor on a form. When I click into the control and press CTRL+A, it selects all of the text.

So I'm not sure why it's not working for you. Maybe something else in your application is using CTRL+A for a shortcut - like perhaps a toolbar or menu item is eating the keystroke so it never gets to the UltraTextEditor.

If you put a regular TextBox control on the same form, does it work?