Man pages matching name xmvacreatemanagedicongadget in section 3:

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