Comment 12 for bug 993275

gvfs-info is detecting that file as:
....
  standard::content-type: text/x-tmplayer
  standard::fast-content-type: image/png

Think I've fixed this upstream.. can anyone try it please?
https://github.com/maxrd2/subtitlecomposer/issues/1

Try replacing /usr/share/mime/packages/subtitlecomposer.xml with this one: https://raw.github.com/maxrd2/subtitlecomposer/6528219ade1f2ca2d78b85a236397aa0d62583ee/src/main/subtitlecomposer.xml and then run:
$ sudo update-mime-database /usr/share/mime

After that running
$ gvfs-info /usr/share/themes/Ambiance/metacity-1/close_focused_normal.png | grep content-type
should give:
  standard::content-type: image/png
  standard::fast-content-type: image/png

Thanks!