Conference bulova::decw_jan-89_to_nov-90

    I'm home so I can't look this up:  Doesn't XtAddInput do what you
    want?  If not, there is an unsupported routine called XMultiplexInput
    which surely does.  Search through the notes file for more info on it.
    
    Burns
    

I think there may be a misconception (started by Mike Collins' example program
in this area...) tht multiple application contexts are needed in order to
support multiple displays.  I believe one application context can support
more than one display.  Using one application context means that you can
simply call XtAppMainLoop (which calls XMultiplexInput and blocks...) and
not do "polling" from your application.

Example (modified from Mike's) follows in next reply.

Leo

    
#include <stdio.h>
#include <DECW$INCLUDE/DwtWidget.h>

#define	CS(x)	DwtLatin1String(x)

Widget		toplevel[2];
XEvent		event;

Widget		CreateToplevel();
void		SetUpTree();
void		quit_callback();
void		error();

DwtCallback	quit[] =   { { quit_callback,NULL}, NULL };

XtAppContext	Context;

char		*display[2] =	{ "node1::0", "node2::0" };

main( argc, argv)
    int	    argc;
    char    *argv[];
{
    int	    n=0;
    int	    start = 0,
	    end = 2;

    XtToolkitInitialize();

    Context = XtCreateApplicationContext();

    for(n=start;n<end;n++)
    {

	toplevel[n] = CreateToplevel(	Context, 
					display[n], 
					argc, 
					argv );

	SetUpTree( toplevel[n] );

	XtRealizeWidget( toplevel[n] );
    };


    XtAppMainLoop (Context);

}   /* End of main program */

    
    
void	quit_callback( w, tag, reason )
    Widget		    *w;
    int			    *tag;
    DwtAnyCallbackStruct    *reason;
{
    exit(0);
}
    
    
    
void error( char	*error_string )
{
    printf( "%s\n", error_string );
}
    
    
    
Widget	CreateToplevel( context, display, argc, argv)
    XtAppContext    context;
    char	    *display;
    int		    argc;
    char	    *argv[];
{
    Display	*dpy;
    Widget	toplevel;
    char	*application_name[] = "SetNode";
    char	*class_name[] = "ClassName";

    dpy = XtOpenDisplay(    context,
			    display,
			    application_name,
			    class_name,
			    NULL,
			    0,
			    &argc,
			    &argv );

    toplevel = XtAppCreateShell(    "TopLevel",
    				    "",
				    topLevelShellWidgetClass,
				    dpy,
				    NULL,
				    0 );

    return( toplevel );
}
    
    
void SetUpTree( top )
    Widget  top;
{
    Widget  mainwidget, pushbutton;

    mainwidget = DwtMainWindow(	top,
				"MainWindow",
				100,
				100,
				100,
				100 );

    XtManageChild( mainwidget );

    pushbutton = DwtPushButton(	mainwidget,
				"PushButton",
				30,
				30,
				CS("Press"),
				quit,
				NULL );

    XtManageChild( pushbutton );
};

    I was using a single application context.  I believe my understanding
    of that area is sufficient not to get into too much trouble.  However,
    my substitute for XtAppMainLoop was incomplete because it did not have
    a call to XMultiplexInput.  It has been added and all is well in
    BuehlerLand.  Thanks to Burns for pointing out XMultiplexInput to me.
    
    Thanks anyway, Leo.  I'm sure it will help others.
    
    The substitute I have for XtAppMainLoop goes more or less like this:
    
    while (1)
       {
        XMultiplexInput(...)
        while (mask = XtAppPending(context))
           XtAppProcessEvent(context, mask);
       }
    
    It appears to work just fine (now).
    
John