I am new to Ubuntu and I just installed ubuntu12.04 for a week. Everything works fine until this afternoon.
Normally, 2 windows of the same application are open, there are 2 grey arrows beside the icon on the panel. When click on the arrows, all the windows from the application line up on window for me to choose. But when I click on it now, nothing happened. The windows are not lining up for me anymore.
I though that maybe I mess with unity too much and broke it, so I tried to reset Unity by
unity --reset and then go to .config/dconf/ to delete the user file. I restart the PC after that.
I realized the feature comes back after the restart, as long as I do not open another type of application. For example, right after the restart, I open three folder windows and all windows line up nicely if I click on the grey arrow. But if I open a Firefox window after that, the feature is gone, no matter how many times I click on the icon, the windows just won't line up.
How can I fix this problem?