Printing white spaces in QPlainTextEdit- the QtCreator way

Hi all, I am trying to understand what's the way to print white spaces inside a QPlainTextEdit (or QTextEdit...) and I am looking for advices - what's the best way to do this?

Can anyone find how/where it's done in QtCreator?

Code:

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QTextOption option =  document()->defaultTextOption();
	if (on)
		option.setFlags(option.flags() | QTextOption::ShowTabsAndSpaces);
	else
		option.setFlags(option.flags() & ~QTextOption::ShowTabsAndSpaces);
	option.setFlags(option.flags() | QTextOption::AddSpaceForLineAndParagraphSeparators);
	document()->setDefaultTextOption(option);

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It seems this functionality has been moved down to QTextDocument:
http://qt.nokia.com/doc/4.6/qtextoption.html#Flag-enum