disable key event when the focus is on autocompletion box of textbox

Question

In my project there is a Form mainForm in which there are two textBoxes txtUserName and txtPassword and also a button btnLogin

Answer 1

You need to override the keydown event handler.

    protected override void OnKeyDown(KeyEventArgs e)
    {
        //call original event handler. Remove it if you don't need it at all.
        base.OnKeyDown(e);

        //Insert your code here....
    }