RE: Backing store 'always' windows & window mapping
RE: Backing store 'always' windows & window mapping
- Subject: RE: Backing store 'always' windows & window mapping
- From: Karl Schultz <email@hidden>
- Date: Tue, 27 Jan 2004 10:49:14 -0700
> -----Original Message-----
> From: Sean Ahern [mailto:email@hidden]
> Sent: Monday, January 26, 2004 12:28 PM
> To: Matthew Klahn
> Cc: email@hidden
> Subject: Re: Backing store 'always' windows & window mapping
>
>
> Hm. While relying on backing store might work for many
> cases, you really
> shouldn't rely on it. From the comp.windows.x FAQ
> (http://www.faqs.org/faqs/x-faq/part7/section-39.html):
>
> 187) Can I rely on a server which offers backing store?
>
> You can assume only that the X server has the capability of doing
> backing store and that it might do so and keep your application's
> visuals up-to-date without your program's involvement;
> however, the X
> server can run out of resources at any time, so you must
> be able to
> handle the exposure events yourself. You cannot rely on
> a server which
> offers backing store to maintain your windows' contents
> on your behalf.
>
> With this in mind, I'd put the blame on IDL.
IDL is an application development language. When the IDL programmer creates
a graphic drawing window, they have the option of specifying the refresh
policy on the window. The user of the IDL application also has some control
over this if the particular IDL application allows it.
The IDL application can specify the refresh policy by asking to always get
expose/map events, get these events only if BS is not avail, and force the
IDL system to use its own backing store so that the IDL application does not
need to handle window repair duties.
So, some of this behavior may depend on the individual IDL application
and/or user default IDL RETAIN settings.
Karl
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