Man pages matching name qwtplotpanner in section 3:

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