Here is the translations for pt_PT (and also for just pt).
These were made from the pt_BR provided earlier. They have minor modifications (only the nuances from Portuguese to Brazilian).
Another thing corrected was the fact that the MyMessages_pt.properties was NOT in UTF-8 and therefore all accentuations were being displayed incorrectly.
Both files (pt_PT and pt) are now in UTF-8 and showing words correctly.
Please be so kind as to include them in the next release of GXT (so that we don't have to manually insert them in the jar file...)