Every couple of minutes all windows are reverted to the default keyboard layout, in per-window mode. Running on xubuntu 11.04 with custom build of the latest version.
The reason seems to be that the callback function is triggered every couple of minutes, resulting in this call-sequence: xfce_xkb_save_config xkb_config_update_settings xkb_config_initialize_xkb_options The last function recreates the g_hash_maps that hold the current window and application settings. So the current settings are lost.
Same seems to happen on xubuntu 12.04, with per application
This looks like the following bug in Ubuntu and Arch: https://bugs.launchpad.net/archlinux/+source/xfce4-xkb-plugin/+bug/944468 https://bugs.archlinux.org/task/16742 There is a patch that supposedly works announced in that thread: https://bbs.archlinux.org/viewtopic.php?pid=639451