Man pages matching name qwtplotzoomer in section 3:

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