@Tom: I'm afraid it is not always that simple...
In Eclipse Juno (4.2), the IPartListener2 notifies about visible-hidden and also about activated-deactivated.
But this does not allow me to reliably determine when a ViewPart is minimized.
visible-hidden is not triggered when minimizing or un-minimizing. It is only used for covering / uncovering windows.
activated-deactivated is triggered when a window is minimized / un-minimized. But it is also triggered when the focus is changed to / from the window while the window is visible. (So actually this seems to be a focusGained-focusLost notification.)
Especially when a minimized window is restored (by pressing the icon with the stacked windows), there is no notification at all because the view does not gain the focus.
Bottom line: For IPartListener2, minimized windows are visible.
The question remains: How can I know when a view is minimized?