void LinesEditor::printWhiteSpaces( QPainter &p )
{		
	const int contentsY = verticalScrollBar()->value();
	const qreal pageBottom = contentsY + viewport()->height();
	const QFontMetrics fm = QFontMetrics( currentFont() );
	
	for ( QTextBlock block = document()->begin(); block.isValid(); block = block.next() )
	{
		QTextLayout* layout = block.layout();
		const QRectF boundingRect = layout->boundingRect();
		QPointF position = layout->position();
		
		if ( position.y() +boundingRect.height() < contentsY )
			continue;
		if ( position.y() > pageBottom )
			break;
		
		const QString txt = block.text();
		const int len = txt.length();
		
		for ( int i=0; i<len; i++)
		{
			QPixmap *p1 = 0;
			
			if (txt[i] == ' ' )
				p1 = &spacePixmap;
			else if (txt[i] == '\t' )
				p1 = &tabPixmap;
			else 
				continue;
			
			// pixmaps are of size 8x8 pixels
			QTextCursor cursor = textCursor();
			cursor.setPosition( block.position() + i, QTextCursor::MoveAnchor);
			
			QRect r = cursorRect( cursor );
			int x = r.x() + 4;
			int y = r.y() + fm.height() / 2 - 5;
			p.drawPixmap( x, y, *p1 );
		}
	}
}