The title should explain everything...
It does look like if the EditText is not Visible then it will not accept focus, however with my Sample attached it DOES work if the EditText is off the screen. If you look at the Layout file in the designer and set zoom to 50% you will see the second EditText.Yes, I already tried that trick, but if the control is invisible it does not accept the focus.
Also if I set it visible and move it off-screen, let's say .left=10000 it does not accept focus.
Visible = True Enabled = False