Setup Hot corners in Ubuntu 12.04

Use the following steps to setup hot corners in Ubuntu 12.04

1. Install 'CompizConfig Settings Manager' from 'Ubuntu Software Center'
2. Go to Category > General > General Options > Key bindings > Show Desktop > Click on 'Disabled' button
3. Select the corner that need to be enabled

Note: In some cases, the hot corner that is set will be forgotten after restarting the machine. In that case, do the following to fix this issue.

1. Install gconf-editor (type gconf-editor in terminal, the command to install will be shown if it is not installed already)
2. After setting the hot corners using CompizConfigSetting Manager, open terminal and type gconf-editor
3. In the Configuration Editor, go to apps > compiz-1 > general > screen0 > options
4. Double click on active_plugins
5. In the Edit Key dialog, move 'scale' to the end of the list, move 'expo' to second last in the list