Version: (using KDE 4.2.4) Installed from: Debian testing/unstable Packages If you start a lot of sessions for a program, then the Task Manager groups them. At this point, you can use "Expand group" to make a lot of icons in the Task Manager. However when you use the "Collapse Parent Group" option (to regroup the expanded group), nothing happens. There seems to be no way to undo the "Expand group" option.
you can middle click on them, and the menu entry works properly in 4.3 as well (i fixed that a while ago in trunk...)