I installed new mouse cursor in my Ubuntu 10.10 and it worked fine, but when I hover in Opera web browser the cursor changes back to default. I found a solution in Ubuntu forums and it works also for this problem in other apps not only in Opera.
Note: this is not a perfect solution that changes in step2 also take effect with other users.
gconf-editor in Alt+F2 pop-up window or a command console.
Then navigate to /desktop/gnome/peripherals/mouse/, remember or copy the value of “cursor_theme” in right. This is the cursor you’re using.
2.) Use following command to edit /usr/share/icons/default/index.theme:
sudo gedit /usr/share/icons/default/index.theme
change the value of “Inherits” to which you copied in Step1(replace words after “Inherits=”, in this case is “Inherits=areo-drop” without quotes).