Add option to disable Event "hover" behaviour
Please describe the problem you are trying to solve
Shotwell 0.30 has new "hover" behaviour on events. Previously, you set a "key photo" and it was static. Now the key photo is the default, but as you move your mouse over the event then the photos rapidly change.
While this is a "cool" feature and might (in constrained circumstances) give a movie-like 'animation' of an event, most events are a mix of significantly different photos. This means that the user doesn't actually see anything from the animation (because they change too quickly) and just gets a flash of different colours.
Because you don't necessarily know what order the photos are in within an event then you can't even use it like a movie timeline (like YouTube's in-video timeline hover previews) because you can't visualise what "before" and "after" might be for any given picture (and from a bit of experimenting then I'm not entirely convinced that they're sequential anyway).
This is made worse when you move your mouse to an event in the opposite corner of the screen, when every event that you move over rapidly flicks through its photos in quick succession.
It would be good to have an option to disable the new key photo behaviour and go back to static key photos to remove the flickering behaviour that doesn't add any functionality.