This will be a tracker for grouping bugs.  I'll start it off by adding the
following dependencies in a minute:
 51574 - don't group indistinguishable items
 52225 - mostly about tasklist sorting, but gives new idea for grouping too
 59692 - make task grouping more intelligent
 60279 - don't group at all if there's sufficient space
 77942 - group titles suck
 80981 - activate last window when clicking on group/don't group active window
 91406 - drag-and-drop to grouped apps
 94683 - support right-click menu on menu items in the group popup
 95211 - click-to-minimize not possible with grouped windows
 96087 - enable moving window "group" to a new workspace
 97491 - do grouping by application "type"
100684 - alphabetize group popup window order
131568 - need minimize all (close all, etc.) entry in rightclick menu
133496 - since grouped windows are first, an abrupt button reordering occurs
139523 - there could be a more visible indication of grouped windows
142569 - grouped windows use the wrong icon
155875 - extend behavior of popup menu for grouped items (group actions, plus
         access to actions for individual windows)

Note that the following Metacity bugs are also somewhat related to "grouping":
 94682 - Alt-F6 to cycle between windows of a group
141171 - move all windows of a group to another desktop