https://invisible-island.net/xterm/xtoolkit/
XtSetArg, XtMergeArgLists - set and merge ArgLists
#include <X11/Intrinsic.h>
int XtSetArg(Arg arg, String name, XtArgVal value);
ArgList XtMergeArgLists(ArgList args1, Cardinal num_args1, ArgList
args2, Cardinal num_args2);
arg Specifies the name-value pair to set.
args1 Specifies the first ArgList.
args2 Specifies the second ArgList.
num_args1 Specifies the number of arguments in the first argument list.
num_args2 Specifies the number of arguments in the second argument
list.
name Specifies the name of the resource.
value Specifies the value of the resource if it will fit in an
XtArgVal or the address.
The XtSetArg function is usually used in a highly stylized manner to
minimize the probability of making a mistake; for example:
Arg args[20];
int n;
n = 0;
XtSetArg(args[n], XtNheight, 100); n++;
XtSetArg(args[n], XtNwidth, 200); n++;
XtSetValues(widget, args, n);
Alternatively, an application can statically declare the argument list
and use XtNumber:
static Args args[] = {
{XtNheight, (XtArgVal) 100},
{XtNwidth, (XtArgVal) 200},
};
XtSetValues(Widget, args, XtNumber(args));
Note that you should not use auto-increment or auto-decrement within
the first argument to XtSetArg. XtSetArg can be implemented as a macro
that dereferences the first argument twice.
The XtMergeArgLists function allocates enough storage to hold the com-
bined ArgList structures and copies them into it. Note that it does
not check for duplicate entries. When it is no longer needed, free the
returned storage by using XtFree.
XtOffset(3)
X Toolkit Intrinsics – C Language Interface
Xlib - C Language X Interface
X Version 11 libXt 1.1.5.2 XtSetArg(3)