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From: han@apple.UUCP (Byron Han)
Newsgroups: comp.sys.mac
Subject: Re: Finding out if there are no windows on the screen
Message-ID: <1036@apple.UUCP>
Date: Mon, 15-Jun-87 11:17:13 EDT
Article-I.D.: apple.1036
Posted: Mon Jun 15 11:17:13 1987
Date-Received: Sun, 21-Jun-87 02:10:37 EDT
References: <8259@ut-sally.UUCP>
Organization: Apple Computer, Inc., Cupertino, USA
Lines: 65
Keywords: Mac Programming Question

In article <8259@ut-sally.UUCP>, brian@ut-sally.UUCP (Brian H. Powell) writes:
> 
>      Motivation:  I'm writing a program that can have several windows and desk
> accessories on the screen.  When there are no windows or DAs on the screen, I
> want the Close item in the File menu to be dimmed.
> 
>      The brute force method is to build the menu each time the user clicks in
> the menu bar.
> 
>      Is there a more elegant solution?  

Try waiting until there is a Null Event returned from GNE.  And then check
to see if FrontWindow = Nil, then disable else Enable

or alternatively, after each MouseDown in the GoAway region of the window, or
each call to SystemClick, check the frontwindow to see if it is
NIL and then disable/enable the CLOSE item.

The second would give better results because if the user clicks in the close
box and has other events queued up immediately after, the CLOSE item may 
not be immediately disabled.  

In fact, the best thing is to do both.  Because, some action in the DA
(via some keydown) may cause the window to go away.  But then you should 
have some sanity checks in the CLose ROutine.  

I typically use this routine which is called in response to a mousedown in the
GoAway part of the window that is the frontwindow (otherwise selectwindow is 
called) or to selecting CLOSE in the FILE menu.

NOTE this is not meant to be final word - there are many ways to improve this
code and this serves as a simple example.  
	
PROCEDURE DoClose;
VAR
	theWindow : WindowPtr;
	theWIndowPeek : WindowPeek;

BEGIN
	theWindow = FrontWindow;
	if theWindow <> NIL do begin
		theWIndowPeek = WindowPeek(theWIndow);
		if theWindowPeek^.windowKind = userKind do begin
			DoCloseMyWindow(theWindow);
		end
		else
			if theWindowPeek^.windowKind < 0 do begin
				CloseDeskAcc(theWIndowPeek^.windowKind);
			end;
	end;
END;

Hope this helps.


=====================================================================
Byron Han            |   UUCP: {sun,voder,nsc,mtxinu,dual}!apple!han
Apple Computer, Inc. |  CSNET: han@apple.csnet 
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employer, Apple Computer Inc.
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