The translate dialog is not working correctly

Bugs:

• If you go through all the words to translate and give up trying to start the search again on the last comparison, and then try to find the next words again and agree to start the search again, the behavior of the dialog box breaks down. The popup dialog box that should appear when the last found match is reached sarts appearing randomly. The same behavior is observed if, before starting the search for a word, we select any word after the one we are looking for and start the search from that place.

• Incorrect behavior was also noticed, if we found a word for us, the "Translate" button is not active, but if we click on the "Match case" checkbox, the "Translate" button becomes active.

I'm attaching a patch that fixes these bugs.