Finally KShortcutsEditor should work 100% correctly regarding applying and undoing changes to local shortcuts.

# KKeySequenceWidget: Improve documentation and document that applyStealShortcut has the side effect of saving an action collection.

That works if you only change one shortcut so keep that method.

# KKeySequenceWidget: Emit a signal if a user agrees to stealing a shortcut. KShortcutsEditor listens to that signal and so hasn't to rely on applyStealShortcut()