Man pages matching name qwtabstractslider in section 3:

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