/* File: helloworld.c */	#include <Xm/Xm.h>	#include <Xm/PushB.h>	void callback(Widget w, XtPointer client_data,		XmPushButtonCallbackStruct *cbs)	{		printf("Hello World!\n");	}	int main(int argc, char *argv[])	{		int n;		Arg args[3];		XtAppContext app;		Widget toplevel, button;		XmString label;		//建立頂級(jí)窗口		toplevel = XtVaAppInitialize(&app, "HelloWorld", NULL, 0,			&argc, argv, NULL, NULL);		//建立按鈕上標(biāo)簽的字符串		label = XmStringCreateSimple("Hello World!");		//建立按鈕		n = 0;		XtSetArg(args[n], XmNlabelString, label);       n++;		button = XmCreatePushButton(toplevel, "pushbutton", args, n);		XtManageChild(button);		XmStringFree(label);		//設(shè)置回調(diào)函數(shù)		XtAddCallback(button, 			XmNactivateCallback,	(XtCallbackProc)callback,			NULL);		//顯示窗口		XtRealizeWidget(toplevel);		//進(jìn)入事件循環(huán)		XtAppMainLoop(app);	}