If an element in the task bar is flashing, the flashing affects other elements: I have a firefox with 3 windows, so 3 elements in the taskbar. If one of them which has a webmailer starts flashing because of new mails, one of the other 2 starts flashing too with the text of the first.
That's taskbar behavior (ie libwnck), not the window manager.
Can't find "taskbar". Product: Xfce4-taskmanager ?
This particular widget is part of libwnck, this is not something we wrote in xfce.
This was rather an issue of sorting. Sorting on group-title and timestamp solved the problem. Sorry for invalid bug report...