[vox-tech] application greyed out

[Kyle Ambroff]

This is a feature of the window manager you are using, in this case
Compiz. Many window managers and implementations implement a protocol
called _NET_WM_PING, which is a way for one X11 client to verify that
another is handling and responding to X11 events.

Not all applications support this protocol, but most do, especially if
they are using a fancy widget toolkit like GTK+ or Qt. An X11 client
can give a hint to the window manager by listing _NET_WM_PING in a
property of its window called WM_PROTOCOLS.

Compiz will periodically send a ClientMessage to the target client
using XSendEvent(), which includes a timestamp. The receiving client
is supposed to respond immediately by sending the same message back to
the sender.

The idea is that each X11 client should have one thread that is
processing events from the X server. If that thread is blocking
because of deadlock, or some operation that is taking a long time,
then it will not respond to these pings in a timely manner. If it is
not processing these messages, it certainly isn't going to be able to
process events from the user, so the window is considered
non-responsive. The desaturation you see is a signal to you that the
application isn't going to be responsive to any input.

Firefox and Eclipse are both large, complicated applications that
share a UI loop with lots of semi-trusted code. It's easy for one of
your extensions, or JavaScript from a web page to block the UI thread.
If you upgrade to a more recent version of Ubuntu, you'll be able to
use FIrefox 3.6, which is *much* better at dealing with this. Or you
could download Google Chrome :).

-Kyle

On Thu, Dec 2, 2010 at 8:04 AM,  <timriley at appahost.com> wrote:
>> -------- Original Message --------
>> Subject: [vox-tech] application greyed out
>> From: Hai Yi <yihai2004 at gmail.com>
>> Date: Thu, December 02, 2010 4:24 am
>> To: "lugod's technical discussion forum" <vox-tech at lists.lugod.org>
>>
>>
>> hello All: I am using ubuntu 9.10, in a quite frequent fashion, I
>> noticed that the whole UI screen of some applications just grey out
>> after working a while, as if they are under heavy resource consuming
>> tasks.
>>
>> So far, this happened to Firefox
>
> This happens to me when using Firefox. It seems to be a reaction
> to the website taking too long to respond. Most likely, it occurs
> when the website starts sending the page but then stops in the
> middle. But this is just a guess.
>
> <snip>
>
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