Enable double buffering in SinglePhotoPage.  Closes #4715, #4716.
Enable double buffering in SinglePhotoPage.  Closes #4715, #4716.
Sanva/shotwell-gsoc,jimbonator/shotwell,abrauchli/shotwell,Sanva/shotwell-gsoc,abrauchli/shotwell,damianmoore/shotwell,polymeris/shotwell,jimbonator/shotwell,damianmoore/shotwell,ritchiewilson/shotwell,h4ck3rm1k3/shotwell,damianmoore/shotwell,abrauchli/shotwell,h4ck3rm1k3/shotwell,h4ck3rm1k3/shotwell,jimbonator/shotwell,polymeris/shotwell,polymeris/shotwell,ritchiewilson/shotwell,ritchiewilson/shotwell,Sanva/shotwell-gsoc