QTextEdit locks up when certain keystrokes are input, but only if NVDA is running.

Windows XP or Windows 8.1, with Latest NVDA - 2014.4.
Simple Application built with QT5.4.1 (Dialog Application with TextEdits - see attached).
Tab into a plaintext edit, and hold down enter, or the right arrow key.
Application (and NVDA) lock up.
Once application killed, NVDA Log suggests that the application simply stops responding when NVDA asks for formatting information (text attributes).

I've submitted this report to NVDA, along with a logfile, and they have concluded that the problem is with QT.

See Here: http://community.nvda-project.org/ticket/4826