I've experienced an issue when using Compiz 0.9 with the Xfce Panel. Say I have a window open on workspace 1 (viewport 1 in Compiz terms). If I right click on the window's titlebar and choose 'Move to Workspace Right' then the window will move to workspace 2 but the window button will still be visible in the panel in workspace 1. If I then switch to workspace 2 and then back to workspace 1 then the window button will have disappeared from the panel in workspace 1 like it should. In essence, the panel needs a viewport switch before it updates the positions the positions of window buttons for windows that have moved to a different viewport. I first experienced the problem in Xfce Panel 4.10.1 (the issue might be older than that even) but I can still reproduce the problem with Xfce Panel 4.11 (I built the 4.11 version from the latest git source a couple of days ago to test). As for Compiz, I'm using 0.9.11 from the bazaar repo.
My distro is Arch Linux 64 bit.
Tested with Compiz 0.8.9 on a different install and had exactly the same issue so this is not specific to Compiz 0.9.
Tested with MATE panel and GNOME panel and the issue does not exist there so this is an Xfce panel problem. I also tried replacing the window buttons plugin with the taskbar plugin but I still experienced the same problem.
Still an issue with Panel 4.12 and Compiz 0.9.12.
Created attachment 6449 patch
I don't really know whether I've fixed this properly but I was fiddling around with the source and eventually stumbled on a solution.
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