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After some experimenting, I think the popup must be contained within and over the component.
Try adding this:
theFrame.setLocation(400, 300); // This causes edit to fail!!! Pop MUST be...

You forgot:
What does it do when you execute it?

It works for me.
I get a small window with a button, I press the button and get a white textfield with a 0. I can enter new data into the textfield.

What does it do when you execute it? What OS...