xfce4-panel-4.9.2 and higher apparently needs it to get the correct aspect ratio in the pager. See the xfce-4.10pr1 release notes [1] and the comment in xfce4-panel git commit a4283dd6 [2] [1] http://www.xfce.org/download/changelogs/4.10pre1 [2] http://git.xfce.org/xfce/xfce4-panel/commit/?id=a4283dd61e894e897ba724f249066bf66c4cd0b1
Also see bug #412823
wnck_pager_set_layout_policy() is used in plugins/pager/pager.c which is behind #ifdef that checks for 2.31 configure.ac checks for 2.30 but I have no problems with forcing more recent versions, long as libwnck-2.31 is fine to stabilize at the end of this month. done that