As per this ml message: http://foo-projects.org/pipermail/xfce4-dev/2006-June/020466.html When an application pops-up a transient, modal window, this should not cause the xfce4-panel to display. This is especially noticeable when the app is in fullscreen because it causes the panel to appear above the app. To reproduce, open firefox in fullscreen mode and press ctrl-D (bookmark this page). The panel will appear so long as the bookmark window is open. My svn revisions: xfce4-panel-svn 21931 xfdesktop-svn 21920 xfwm4-svn 21934 libxfce4mcs-svn 20976 libxfce4util-svn 21851 libxfcegui4-svn 21895 Scott
Of course it does, that's on purpose. If an application is fullscreen, it should be sent back on the regular layer if it looses focus, otherwise a blocking window would not be seen.
Ok, that's changed/fixed is SVN
Closing then, minimum revision is 22092, but compositor in svn is still under a big rework and not be stable (yet, hopefully), so you may chosse to wait before upgrading or disable compositor for testing.