If this is of interest for developers, I found that in libwnck-2.28.0 (karmic) the persistent tooltips in the window list applet can be avoided by applying a patch to 'tasklist.c' that disables tooltips only in 'wnck_task_update_visible_state'.
In libwnck-2.26.0 (jaunty) it was necessary to disable tooltips also in 'wnck_task_popup_menu' and 'wnck_task_create_widgets' (see comment #33).
If this is of interest for developers, I found that in libwnck-2.28.0 (karmic) the persistent tooltips in the window list applet can be avoided by applying a patch to 'tasklist.c' that disables tooltips only in 'wnck_task_ update_ visible_ state'. popup_menu' and 'wnck_task_ create_ widgets' (see comment #33).
In libwnck-2.26.0 (jaunty) it was necessary to disable tooltips also in 'wnck_task_