[gtk] (12 commits) ...Merge branch 'matthiasc/for-master' into 'master'

[Matthias Clasen <matthiasc src gnome org>]

Summary of changes:

  f54ed6f... columviewsorter: Add an assertion (*)
  2d1135f... applicationaccels: Plug a leak (*)
  df01c5c... columnlistitemfactory: Plug a leak (*)
  497d137... filechoosernativewin32: Plug a leak (*)
  c55dd10... placessidebar: Plug a leak (*)
  3a43859... Cosmetics (*)
  edb7925... printunixdialog: Plug a leak (*)
  6c1217d... filter tests: Plug a leak (*)
  f94f325... filterlistmodel tests: Plug a leak (*)
  ee96bc7... multiselection tests: Plug a leak (*)
  87b5ead... treesorter tests: Add a comment (*)
  ddb9e42... Merge branch 'matthiasc/for-master' into 'master'

(*) This commit already existed in another branch; no separate mail sent