Man pages matching name xmvacreatelabelgadget in section 3:

XmVaCreateLabelGadget.3.en	debian 10 / libmotif-dev
XmVaCreateLabelGadget.3.en	debian 11 / libmotif-dev
XmVaCreateLabelGadget.3.en	debian 12 / libmotif-dev