You need to change the line which creates the GUI figure, as for some screen resolutions (e.g. 1280x800, a common laptop resolution), the GUI appears halfway off the top of the screen.
Also, a minor point - is it possible to make the text in the text box become selected when you click in it, so that you can type right away without deleting the text first?
currently sets the position property to [500, 400, 420, 500], which, if you're using a laptop with resolution 1280x800 for example (a common screen size),
As a gui tool that is so easily used, and so obvious in its use, I'm conflicted. I'd happily give this a rating of 5 in a heartbeat as a dictionary tool. Every actual word I tested it with was provided with a definition.
The code itself appears to be well written, using a self-documenting style with descriptive variable names. This helps when there is perhaps a Java problem in the future.
What I don't like is the fact that it has not a single line of help in the file. Again, yes, it is a gui. But it lacks an H1 line, so that lookfor will fail if you try to find this function a year from now.
This is a good code. It could easily have been a splendid one.