[gtk] (8 commits) ...Merge branch 'bilelmoussaoui/g-i' into 'main'

[Matthias Clasen <matthiasc src gnome org>]

Summary of changes:

  85bb9aa... g-i: add nullable annotation to gtk_single_selection_get_mo (*)
  cb710f1... g-i: mark EventController::name as nullable (*)
  6b63868... g-i: mark get_selected_printer as nullable (*)
  e6322e1... g-i: Mark get_print_settings as nullable (*)
  ba26632... g-i: Mark FileChooser [s|g]et_current_[folder|name] as null (*)
  c2fe438... g-i: Add nullable annotations to CellArea getters (*)
  3b38356... g-i: Add nullable annotations to EventControllerKey::im-con (*)
  d2a2591... Merge branch 'bilelmoussaoui/g-i' into 'main'

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