Man pages matching name xmvacreatemanagedsimplespinbox in section 3:

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