This extension turns the Activities button into two button with icon or text to select Applications or Workspaces in the Overview. Change the same view for button to icon or text.
Note: Binary files aren't shown on the web site. To see all files, please download the extension zipfile.
It would be a good idea to connect/disconnect from your "changed" signal in enable()/disable(), instead of init(). It might not be obvious, but the signal could be emitted while the extension is either disabled or enabled, since users can access the preferences dialog while the extension is disabled. Not a deal breaker though :)
Apps to Panel