Fix set/unset range thumbnails
On a very slow machine, in the gallery when I scroll horizontal, sometimes the previous thumbnail is half visible and so the method eog_thumb_view_clear/add_range is called repeatedly and load/unload this range.
The commit 94e2029e fix this problem by only unloading the second previous thumbnail. That mean :
we unload this thumbnail | Still loaded | The first visible thumbnail |
---|---|---|
Image 1 | Image 2 | Image 3 |