Very brief window list in AWN

[GuyFawkes]

Hello.
I use Fedora Core 16. I have AWN, and when I open a group of similar windows, or some application opens them itself, AWN is grouping them to one icon, and I can choose a window from the list by clicking on the icon.

But, a while ago, the window list was shown very briefly:



How I can to fix it? Thank you.