[gtk] (13 commits) Non-fast-forward update to branch stack-fixes

[Matthias Clasen <matthiasc src gnome org>]

The branch 'stack-fixes' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  e403b69... gtk: Add GtkSelectionModel
  f048b48... gtk: Add GtkSingleSelection
  a9cebeb... keep single selection private for now
  6ea1eaf... Fix single selection to notify
  2c7a55c... wip: stack: use a selection model
  59fd111... Add docs
  9df8cce... Convert the sidebar too
  a45fc9d... stack switcher: Cosmetic changes
  a65826a... gtk-demo: Fix the sidebar demo
  9991747... stack: Drop the position property
  91f5b71... Test fixes

Commits added to the branch:

  2eaffe4... Update Polish translation (*)
  37d218b... imwayland: Toggle OSK more sparingly (*)
  58eb1c9... Merge branch 'wip/carlosg/toggle-osk-sparingly-master' into (*)
  fa447c6... gtk-demo: Fix the sidebar demo
  c106436... gtk: Add GtkSelectionModel
  d4f4626... gtk: Add GtkSingleSelection
  00581c6... Keep GtkSingleSelection private for now
  ea403ab... Fix GtkSingleSelection property notification
  694bb89... stack: Provide a selection model
  1b7d2a9... stackswitcher: Use a model
  b4d600e... sidebar: Use a model
  f18027f... stack: Drop the position property
  4df0853... Fix problems with the no-selection state

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