QTextBlockFormat.setForeground is useless?

[sonichy]

QTextBlockFormat.setBackground is good, but QTextBlockFormat.setForeground is useless!
https://github.com/sonichy/Qt_QQMusic

QTextCursor cursor1(ui->textBrowser->document()->findBlockByLineNumber(hl));
QTextBlockFormat TBF1 = cursor1.blockFormat();
TBF1.setForeground(QBrush(Qt::green));
TBF1.setBackground(QBrush(Qt::yellow));
cursor1.setBlockFormat(TBF1);
ui->textBrowser->setTextCursor(cursor1);