Skype /alertsoff doesn’t work on Mac

make repost of this bug, because there is still no response.

I’m participating in some groups. I try to turn off any notification and sounds in this group.
I tested /alertsoff on Lion and Win7. It works correctly on Win7, but doesn’t work on Lion. I see notifications in Dock. Please see the screenshot.

if somebody knows how to solve it – please help.