Unexpected blank line before QTextFrame

[YuriQ]

Hello.
I use Qt 5.2.1 under Windows 8.1. Please take a look at the sample code:
@
int main( int argc, char *argv[] )
{
QApplication app(argc, argv);

QTextEdit editor;
QTextCursor cur(editor.document());

QTextFrameFormat fmt;
fmt.setBorder(1);
fmt.setPosition(QTextFrameFormat::Position::FloatLeft);
fmt.setPadding(0);
fmt.setMargin(0);

for (int i = 0; i < 10; i++)
{
cur.movePosition(QTextCursor::Start);
QTextFrame* frame = cur.insertFrame(fmt);
frame->firstCursorPosition().insertText("sample text");
}

editor.show();
return app.exec();
}
@

The code above just adds few frames with text in QTextEdit widget. Everything is ok except one blank line in the beginning of QTextEdit's content. Why this blank line appears? What should I do to prevent appearing of blank line?