Prevent short cut key in date time picker

You can use the SuppressKeyPress property in the KeyDown evnt of your DateTimePicker, like this:-

private void dateTimePicker1_KeyDown(object sender, KeyEventArgs e)
        {
            if(e.KeyCode == Keys.F4)
            {
                e.SuppressKeyPress = true;
            }
        }

and that will prevent F4 from working.

Hope this helps.