[gthumb-list] gthumb 3.3.1 : gtk(3) theme broken?

[Kristian Rink <kawazu428 gmail com>]

Folks;

running gthumb on Debian unstable, it seems this recently (yesterday?) 
upgraded to a version 3.3.1, and it seems broken in two ways:

(a) The gthumb UI doesn't honour the GTK(3) theme settings anymore but 
displays in a somewhat dark, unconfigurable theme.

(b) The menu bar, apart from the navigation / slideshow / tool buttons, 
is completely transparent and always makes me see through whichever 
window lies "under" the gthumb window (and be that the root window / 
desktop background).

Changing the GTK theme doesn't change much. Is anything I can do to get 
gthumb back to normal and to seamlessly blend with the rest of my GTK 
applications?

TIA and all the best,
Kristian