Created attachment 255503 [details]
screenshot from overview with "Workspaces only on primary monitor" disabled

I disabled the "Workspaces only on primary monitor" setting, and now my secondary monitor switches workspaces when the primary one does. This is fine. But the workspace switcher in the overview only displays the part of each workspace corresponding to the primary monitor. I can put windows in the second workspace, but they are not visible in the workspace preview. 

It's so easy to loose track of a window this way that it can't be the intended behavior. The thread linked below was started by people who seem to have the same problem, but no one's answered it even though gnome has gone through two major releases since then.

http://ubuntuforums.org/showthread.php?t=1973027

Judging from that conversation, not everybody has this problem when they disable the "Workspaces only on primary monitor" option. I could not figure out what was different about systems that have this problem. 

My system:

Fedora 19
Gnome 3.8.4
NVIDIA GeForce GTX 460

Both the Nouveau and proprietary NVIDIA graphics drivers behave the same.