Comment 4 for bug 878620

I can confirm that this behavior has been happening to me since migration to Oneiric. To be more precise, this is the orange "effect" that appears underneath a window when it is "snapped" to the left or top of the screen to maximize it.

It can be triggered by moving the mouse to the left side and is triggered before Dash appears. Using Expo Key <Super-s> s to display the workspaces and move the mouse a bit will make the effect disapear.