How can I disable workspaces for external monitor?

How can I disable workspaces for the external monitor in Maverick Meerkat (10.10)?

Basically, I want to use the ability to switch workspaces, but on the main monitor only, I would like to set a fix window (for example a media player) on the external monitor. Is this possible?

If I cannot do that, is it possible to "pin" windows so they are visible on all workspaces?

Some advanced window managers (eg. xmonad) make it possible to assign workspaces to individual screens independently. But if you prefer to stick to Unity and Compiz, just right-click on the top bar of a window and select "Always on Visible Workspace". (You have to unmaximize the window first.)