Motif

#include <Xm/XmAll.h>

void main(int argc, char *argv[])
{
    Widget toplevel, main_w, button;
    XtAppContext app;

    XtSetLanguageProc(NULL, NULL, NULL);

    toplevel = XtVaAppInitialize(&app, "main", NULL, 0,
                                 &argc, argv, NULL, NULL);

    main_w = XtVaCreateManagedWidget("main_w", xmMainWindowWidgetClass,
                                     toplevel, XmNscrollingPolicy, 
                                     XmAUTOMATIC, NULL);

    button = XtVaCreateWidget("Hello World", xmLabelWidgetClass, main_w, NULL);

    XtManageChild(button);
    XtRealizeWidget(toplevel);
    XtAppMainLoop(app);
        
}