Inconsistent sibling-folder-jump in fullscreen mode

[wOxxOm]

Options:
DblClick: Browser <> Fullscreen | Viewer <> Fullscreen
Middle: Browser <> Fullscreen | Viewer <> Fullscreen
Enter: Browser -> Fullscreen -> Viewer

Parent folder
-- ImageFolder1
-- ImageFolder2 (active)
-- ImageFolder3

Behaviour:
1. <Enter> in FileList :: now in fullscreen, go to the last image, press a key to advance to the next image (PgDn) - nothing happens (bug)
2. <F11> / <DblClick> in FileList :: now in fullscreen, everything works fine