After playing with this a bit more. I found that pressing Enter in a text field causes it to lose focus. So, my guess is the problem you are seeing is the order of events.
Your button is getting the Enter press, then your text field is getting the enter press. When the button gets the enter press, it clears the box and gives it focus, but then I think the text field is then getting the enter press which causes it to lose focus.
Funny thing is, the text field does not give any events when it gets the enter press except EVENT_GADGETLOSTFOCUS. I tried this without the button and the text field loses focus on Enter, sends the EVENT_GADGETLOSTFOCUS and that is it.
Your button is getting the Enter press, then your text field is getting the enter press. When the button gets the enter press, it clears the box and gives it focus, but then I think the text field is then getting the enter press which causes it to lose focus.
Funny thing is, the text field does not give any events when it gets the enter press except EVENT_GADGETLOSTFOCUS. I tried this without the button and the text field loses focus on Enter, sends the EVENT_GADGETLOSTFOCUS and that is it.