Re: new cygwin/x11 and backingstore

[Jon TURNEY <jon dot turney at dronecode dot org dot uk>]

On 04/02/2010 15:25, anne crespy wrote:
> Hi,
>
> Before updating Cygwin/X with the new version (X11R7) I launched Xwin with this
> command :
>
> XWin -multiwindow -clipboard -silent-dup-error +bs&
>
> and the backingStore option worked correctly in a graphic window (built with
> tcl/tk8.4 and Xlib).

You were just lucky :-)

The backing store attribute is a hint; the server doesn't have to
honour a request to use backing store.

Note that even if you have an X server which does provide backingstore, the 
server doesn't have to provide an unlimited amount of memory for it, so it may 
discard backingstore at any time.

Any X client which *requires* backingstore to work is broken, not correctly 
redrawing windows when they are exposed.

See [1]

> Now, it doesn't work. When the graphic window is overlapped its contents is
> corrupted by the top window.
>
> I didn't have this problem with the beta-version in november 2009.
>
> What have changed since?

backingstore is implemented in terms of Composite in the X.Org server since X 
server 1.5.0

Unfortunately, we have had to disable Composite in the current X server due to 
crashes.

If/when these problems with Composite are fixed, things may work a little 
better...



[1] http://www.mail-archive.com/xorg@lists.freedesktop.org/msg04440.html

--
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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