Peter Harris pharris at
Wed Apr 8 08:36:33 PDT 2009

Michel Dänzer wrote:
> On Wed, 2009-04-08 at 10:30 -0400, Patrick O'Donnell wrote:
>>> From: Michel =?ISO-8859-1?Q?D=E4nzer?= <michel at>
>>> Date: Wed, 08 Apr 2009 15:58:18 +0200
>>> On Wed, 2009-04-08 at 09:55 -0400, Patrick O'Donnell wrote:
>>>>> From: Michel =?ISO-8859-1?Q?D=E4nzer?= <michel at>
>>>>> Date: Wed, 08 Apr 2009 15:29:28 +0200
>>>>> On Wed, 2009-04-08 at 09:14 -0400, Patrick O'Donnell wrote:
>>>>>> Unfortunately, that's not going to be available for all the platforms
>>>>>> we must support.
>>>>> Why not?
>>>> Ummmm...  Because the servers on those platforms do not offer it?
>>> What are 'those platforms'? Which servers offer neither the
>>> Composite extension nor backing store?
>> The world is not all  Not all the X servers on Windows that we
>> have to deal with offer the Composite extension (or backing store --
>> sigh).
> Ah, I thought this was about changes making things worse for you.
> Guess I lost track. :}

It is. New servers dropped SaveUnders. Many other X servers
(including builds from a couple of years ago) don't have the
purported replacement. Now he has to support both. Needing to support
both is worse than having to support only one.

Honestly, SaveUnders and BackingStore were always just hints, so relying
on them has always been broken. But that doesn't make his life any
easier just now, so I can understand his frustration.

As a constructive suggestion: For expensive drawing, you can draw to a
pixmap and just copy from that pixmap to the window every time you get
an Expose event. This should require relatively small changes to your
code, and will work on all servers. The main downside is the lack of
visible user-feedback while drawing, so you may want to implement a
swirly or a progress bar or something so your users don't think the app
has hung.

Peter Harris
               Open Text Connectivity Solutions Group
Peter Harris          
Research and Development        Phone: +1 905 762 6001
pharris at            Toll Free: 1 877 359 4866

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