I installed gThumb via apt (v 3:3.4.3-1). Unfortunately it doesn't show preview images of raw photos (Panasonic's *.rw2). The raws contain definitively a preview since geeqie displays them as expected.
How do I activate the raw preview? Do I need to compile gThumb by myself (I tried but failed because
No package 'gsettings-desktop-schemas' found although installed.)?