QPlainTextEdit ignores the Cmd modifier on OS X

On OS X holding down the Cmd key and typing a text key, for example Cmd+k causes k to be added to the text. This is a regression from Qt 4. Simple PyQt test script is attached, run it, Type Cmd+K.

Workaround is to override keyPressEvent and reject key events that have the Cmd modifier and text content, but this is less than optimal it has the potential to interfere with copy/paste shortcuts.