This my initial port to KGlobalAccel. It is certainly far from perfect considering it is my first time using it.
We can now easily have an Editor for the shortcuts inside the Application thanks to KShortcutsEditor.
One regression to the current solution with KHotkeys is that it only works when Spectacle is running. An idea to work around this could be autostarting
Spectacle in DBus mode. Also I didn't know where to place the KActionCollection and put it in SpectacleConfig.