I've reported this in the Gnome bugzilla:
https://bugzilla.gnome.org/show_bug.cgi?id=619270
** Bug watch added: GNOME Bug Tracker #619270
https://bugzilla.gnome.org/show_bug.cgi?id=619270
** Also affects: gnome-panel via
https://bugzilla.gnome.org/show_bug.cgi?id=619270
Importance: Unkno
** Attachment added: "Dependencies.txt"
http://launchpadlibrarian.net/48820966/Dependencies.txt
** Attachment added: "GConfNonDefault.txt"
http://launchpadlibrarian.net/48820967/GConfNonDefault.txt
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"group windows when space is limited" isn't configurable
https://bugs.launchpad.net/bugs
Public bug reported:
Binary package hint: gnome-panel
In the Window List preferences, I set Window Grouping to "group windows
when space is limited". The grouping only kicks in when the buttons
become very small. The threshold appears to be 80 pixels
(libwnck-2.30.0/libwnck/tasklist.c line 94, #d