https://invisible-island.net/xterm/xtoolkit/
XtAddActions - register an action table
#include <X11/Intrinsic.h>
void XtAddActions(XtActionList actions, Cardinal num_actions);
actions Specifies the action table to register.
num_args Specifies the number of entries in this action table.
XtAddActions has been replaced by XtAppAddActions.
XtAppAddActions(3)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
X Version 11 libXt 1.3.1 XtAddActions(3)