Our custom Undo not working when tool lose focus

[piXelicidio]

The tool undo system is custom made and replace Unity undo intervening Ctrl-Z,Y shortcuts.
When the Scene View and the tool window lose the focus in some circumstances the Unity Undo is triggered and mess everything.

how to reproduce: Clicking other game objects in the Hierarchy panel, Ctrl+Z

[piXelicidio]

Was getting input from OnSceneGUI() only. When the editor window is focused needs separated processing of events, from OnGUI().