Desktop Entry %f does not work, needs %U

[Andreas Wehler]

Xubuntu 16.04; gpicview 0.2.5; XFCE

From within shutter some image can be launched via right mouse: "Open With".
If gpicview is selected, some image from home directory is presented, instead of
the related image. Other viewers like eog don't show this effect but open the
right file.

Investigation shows, that in /usr/share/applications/gpicview.desktop there
is a line:

  # BAD
  Exec=gpicview %f

If this is replaced by:
  # GOOD
  Exec=gpicview %U

then it works. Seems there has to be some debugging about this issue.
I cannot tell if shutter or gpicview is wrong. But I assume gpicview
to be wrong because other viewers / browsers do it right.

https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html