Crash when wrapping of commit messages

I found a crash when input multi-byte for commit message.
See this commit:

From 2fc4e9001522808484666c98bda25987dfccc91b Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@nokia.com>
Date: Fri, 20 Mar 2009 16:02:14 +0100
Subject: [PATCH] Fix wrapping of commit messages

Remove trimmedDescription(), always trim. Extract trimmed text using the
text cursor
Reviewed-by: Thorbjorn Lindeijer <thorbjorn.lindeijer@nokia.com>

diff --git a/src/libs/utils/submiteditorwidget.cpp b/src/libs/utils/submiteditorwidget.cpp
index db559a2..687813c 100644
— a/src/libs/utils/submiteditorwidget.cpp
+++ b/src/libs/utils/submiteditorwidget.cpp
...
+
+// Extract the wrapped text from a text edit, which performs
+// the wrapping only optically.
+static QString wrappedText(const QTextEdit *e)
+{
+ const QChar newLine = QLatin1Char('\n');
+ QString rc;
+ QTextCursor cursor(e->document());
+ cursor.movePosition(QTextCursor::Start);
+ while (!cursor.atEnd())

Unknown macro: {+ cursor.select(QTextCursor}

+ return rc;
}

QString SubmitEditorWidget::descriptionText() const
{

• QString rc = m_d->m_ui.description->toPlainText();
  + QString rc = trimMessageText(lineWrap() ? wrappedText(m_d->m_ui.description) : m_d->m_ui.description->toPlainText());
  // append field entries
  foreach(const SubmitEditorWidgetPrivate::FieldEntry &fe, m_d->m_fieldEntries) {
  ...

The crash happend in this statement:

cursor.movePosition(QTextCursor::Right);

Here is happend a ASSERT failed:
qt-everywhere-opensource-src-4.7.4\src\gui\text\qtextcursor_p.h (line: 78)

inline bool setPosition(int newPosition) {
Q_ASSERT(newPosition >= 0 && newPosition < priv->length());
bool moved = position != newPosition;
if (moved)

Unknown macro: { position = newPosition; currentCharFormat = -1; }

return moved;
}

I am from chinese, when when I input some chinese word (Multi-byte), then QTC crash.
I try to fix, but I found this perhaps Qt's bug.
Any comments?