I have found that, for a while now, SQL syntax highlighting breaks when I switch tabs (to another document) and then switch back (to the SQL file). I have included 2 screenshots, you can see in SQL_Incorrect.png that, after the first String2 occurrence, the rest of the file has been colored as the "SQL : STRING2" style after switching tabs.
I have just upgraded to v6.5.2 UNICODE, but this has been happening for at least a few versions prior.
Let me know if you need any further information.
Jeff Evans, Jr.