I've an issue in an Ubuntu install that was upgraded to 12.04. Recently the Unity Launcher is behaving strangely: left-clicking the dash icon changes the title bar and a triangle appears next to it, suggesting that it is running but nothing else can be seen, It does not respond to keyboard input either. Using the "Super" key produces the same result (or lack of thereof).
Right clicking on the dash icon only shows "Dash home" and it has the same non-effect as above. The red line is something new that wasn't there when the "Dash home" button worked correctly (yes this worked after the initial upgrade but broke later (cause unknown).
The suggested solution
sudo compiz --replace revives the "Dash Home" button (--restart complains about already having a window manager) but it also breaks the window manager and the terminal window used to issue it becomes an orphan among other things.
Curious to hear what the reason for the behavior might be and what could bring it back to normal function again?