Changing desktop background in OS X 10.8 only changes it for the current desktop space

I'm experiencing a bug in Mountain Lion. I have 2 desktop spaces open. When I change the desktop background picture, it only changes for one of the spaces and not the other. Rebooting solved the problem.

Is this a bug? If so what is causing it? Is there any way to change the behaviour?

Seems like if you set the first desktop to the picture you want and then go to each space and right click on the desktop and select "Change Desktop Background" it changes that desktop's background to the background of Desktop 1.

YMMV: This in 10.8.1, pretty sure it wasn't like that before (in 10.8).

1. Go to Mission Control and remove all Spaces but the Main Space (which is the leftmost space) by clicking the "X" buttons at their upper left corners.
2. Click the Main Space to enter it and chose the desired desktop background.
3. Go to Mission Control again and add the desired amount of spaces by repeatedly moving the mouse pointer to the upper right corner of the screen and clicking the "+" Button that will emerge.
4. Voilà: every new space will have the same background.

As Alex pointed out. I falsely assumed workspaces was the same as in 10.6 where all workspaces backgrounds change simultaniously. This is not the case in 10.8. Meaning my bug is not a bug, it's a feature.

It's an annoying issue but I found a decent solution.

1. Open up the system preferences pane and choose Desktops&Screensavers.
2. Choose your background of choice for the current Space that the preference pane is open in. Only the background in this space will change.
3. Activate Mission Control and drag the system settings preference pane to your next Space that you'd like to change.
4. Click on a picture within the Desktops&Screensavers pane that you'd like for this background and it'll change for this current Space.
5. Repeat the Mission Control and dragging the preference pane as necessary for other Spaces.