[Feature Proposal] Show app's icons on workspaces preview.

[juanlb]

I think it is a good idea to add the possibility to select what to show in the preview of each workspace:

• the thumbnail of each screen (current behavior)
• a list of icons of the open applications.

I'm used to having more than one application open in each workspace, and I think showing the icons is more useful than just the thumbnail on the screen. This way you can identify at a glance which workspace you need to jump into.