Man pages matching name qwtscalewidget in section 3:

QwtScaleWidget.3.en	debian 10 / libqwt-doc
QwtScaleWidget.3.en	debian 10 / libqwt5-doc
QwtScaleWidget.3.en	debian 11 / libqwt-doc
QwtScaleWidget.3.en	debian 12 / libqwt-doc