[gtk] (9 commits) ...Merge branch 'matthiasc/for-master' into 'master'

[Matthias Clasen <matthiasc src gnome org>]

Summary of changes:

  5379a4b... a11y: Clean up properly in unregister_object (*)
  b622745... gtk-demo: Plug a memory leak (*)
  b81463e... gtk-demo: Plug a memory leak (*)
  6fa2936... gtk-demo: Set default size for drawingarea demo (*)
  7d49f1e... gtk-demo: Improve consistency (*)
  a85d9cd... gtk-demo: Improve consistency (*)
  14be508... gtk-demo: Improve consistency (*)
  a745dbf... gkt-demo: Add a columview to the scroll demo (*)
  2543c9f... Merge branch 'matthiasc/for-master' into 'master'

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