I can confirm this bug. The problem is apparently that the icon itself is not sensitive to clicks. You have to click on the surrounding area to get the action performed (a hint of this is that whe hovering the pointer over the icon, the highlight of the tray button disappears).
As the original reported pointed out, using the keyboard serves as a workaround, and also clicking on the surrounding area (the edges of the button, when the icon is rendered in a big size like gnote's or clipit's). -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org