Comment 54 for bug 858845

I can confirm that expo/scale hot corners don't work in 14.04 . This is an Intel machine (ironlake gpu) , so it has nothing to do with Nvidia or nouveau.

Also the workarounds that involve re-ordering the plugins in ccsm (disable auto-sorting) and /or dconf/gconf editor for previous versions of Ubuntu don't work anymore. In 14.04 expo hot corner won't work unless it is at the very bottom of the list. Scale cannot be further down than Unity shell or initiating scale would kill unity.

A work around would be to add the command "unity --replace" to startup application. It works, but very ugly.