fixes #1819 drag and drop export is broken
fixes #1819 drag and drop export is broken

jof/shotwell,jof/shotwell,Sanva/shotwell-gsoc,h4ck3rm1k3/shotwell,abrauchli/shotwell,jimbonator/shotwell,damianmoore/shotwell,jof/shotwell,h4ck3rm1k3/shotwell,damianmoore/shotwell,polymeris/shotwell,h4ck3rm1k3/shotwell,jimbonator/shotwell,Sanva/shotwell-gsoc,ritchiewilson/shotwell,ritchiewilson/shotwell,ritchiewilson/shotwell,Sanva/shotwell-gsoc,abrauchli/shotwell,polymeris/shotwell,jimbonator/shotwell,abrauchli/shotwell,polymeris/shotwell,damianmoore/shotwell