Edit a inspector variable from editor script.(its not saving)

I need to give my objects of a same parent class a different ID.
I wrote a editor script to do this and that works.

But when I save and load the scene, the ID have their default values again.

The parent class that hold the ID:

public class SavableClass extends MonoBehaviour
{
	public var uniqueSaveID : int;
}	

The editor script:

public class SaveIDsManager extends ScriptableWizard
{
	new function OnGUI() :void
	{
		if(GUILayout.Button("Set Save ID's")) 
		{
			SetIDs();
		}
	}
	
	function SetIDs() :void
    {
    	var SavableClasses 	: SavableClass[]	= FindObjectsOfType ( SavableClass );
    	
    	for ( var saveScript : SavableClass in SavableClasses )
		{    			
			// If no ID
			if ( !saveScript.uniqueSaveID )
			{
				saveScript.uniqueSaveID = FindFreeID();
			}
		}
		
		function SetIDs() :int
    	{
    		// code checking what id is next
    		var availebleID : int = 10;
    		return availebleID;
    	}
    }
}

Found it, I must mark the edited script as ‘dirty’ by adding this code on line 21 in my editor script posted in the main post:

EditorUtility.SetDirty ( saveScript );