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From: shap@bunker.isc-br.com (Joseph D. Shapiro)
Newsgroups: comp.windows.ms.programmer
Subject: Re: Does a window know when it is being overwritten?
Message-ID: <19209@bunker.isc-br.com>
Date: 6 May 91 16:53:25 GMT
References: <59847@siemens.siemens.com>
Reply-To: shap@clunker.UUCP (Joseph D. Shapiro)
Organization: ISC-Bunker Ramo, an Olivetti Company, Shelton, Ct
Lines: 23

In article <59847@siemens.siemens.com> jrv@demon.siemens.com writes:
: Does a window know when it is being overwritten?  The potential exists
: whenever the input focus is lost.  The focus will be lost whenever another
: application is brought up on top of my client area.  This is also true when
: my application brings up a dialog box.  For drop down menus and child windows
: I don't think that is true.  I have control over when the child window will
: appear.  I don't recall any message sent just before a menu is dropped.  The
: basic problem is that before anyone overwrites part of my client display
: memory, I have to save the pixels which will be overwritten.  I don't have
: another copy of the pixel data.  It has been generated by a coprocessor on
: the display card running some algorithms on my image data.  I could keep a

hi.  Somebody else already posted about the message you get when a menu
is about to drop.  But did you know that the pixels under the menu are
automatically saved and restored?  This gets a little more difficult if
you continue to draw on the window when the menu is down, and it might
also be confounded by your video processor, but take it for what it is
worth.
-- 
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Joe Shapiro					"My other car is a turbo...
ISC-Bunker Ramo     				 ...too."
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