Path: utzoo!attcan!uunet!lll-winken!ames!hc!eggroll!pprg.unm.edu!unmvax!tut.cis.ohio-state.edu!bloom-beacon!earth.cray.COM!jlf
From: jlf@earth.cray.COM (John Freeman)
Newsgroups: comp.windows.x
Subject: confusion about "application contexts"
Message-ID: <8902161733.AA15972@thelake.cray.com>
Date: 16 Feb 89 17:33:19 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 63


I have had the same questions about application contexts.
I sent a posting to xpert last week and have seen no
responses to it.  However, since then, I have been able
to get some things to work with application contexts,
a sample 'Hello, World.' is enclosed using appcontext.

> Just what are applications contexts for?

Well, although the data type XtAppContext is opaque,
if you look at it, you'll find it does have a pointer
to a list of displays, allowing the programmer to 
bring up widgets/windows on multiple displays.  (See
the example) It also has a resources pointer, 
meaning each AppContext could have different resource 
specifications.  Beyond that, they still mystify me.

----------------------------------------------------------------------------
/* "Hello, World" on two displays - John L. Freeman, Cray Research Inc. */
#include <X11/Xlib.h>
#include <X11/Intrinsic.h>
#include <X11/StringDefs.h>
#include <X11/Shell.h>
#include <X11/Label.h>
#include <stdio.h>
#define STRING1 "Hello, World!"
#define STRING2 "Goodbye, World!"

Arg label1_args[] = {XtNlabel, (XtArgVal) STRING1 };
Arg label2_args[] = {XtNlabel, (XtArgVal) STRING2 };
Arg argies[5];

main(argc,argv)
int argc;
char **argv;
{
    Widget top1, top2, label1, label2;
    Display *d1p, *d2p;
    XtAppContext app1;

    XtToolkitInitialize();
    app1 = XtCreateApplicationContext();

/* Sun 3/60 named "thelake" using screens 0 and 1 */
d1p = XtOpenDisplay(app1, "thelake:0.0", NULL, "Xlabel", NULL, 0, &argc, argv);
    if (d1p == NULL) { printf("XtOpenDisplay failed\n"); return; }
d2p = XtOpenDisplay(app1, "thelake:0.1", NULL, "Xlabel", NULL, 0, &argc, argv);
    if (d2p == NULL) { printf("XtOpenDisplay failed\n"); return; }

    top1 = XtAppCreateShell("XShell", "xshell",
	applicationShellWidgetClass, d1p, NULL, 0);
    top2 = XtAppCreateShell("XShell", "xshell",
	applicationShellWidgetClass, d2p, NULL, 0);

    label1 = XtCreateManagedWidget(argv[0], labelWidgetClass,
	    top1, label1_args, XtNumber(label1_args));
    label2 = XtCreateManagedWidget(argv[0], labelWidgetClass,
	    top2, label2_args, XtNumber(label2_args));
    XtRealizeWidget(top1);
    XtRealizeWidget(top2);

    XtAppMainLoop(app1);
}