I noticed that the managers (e.g. G4RunManager (and G4TrackingAction, G4SteppingAction, etc)) delete their user actions (e.g. userRunAction) in their destructors. This seems strange, because the user actions are always allocated outside of the managers. Without a method to explicitly transfer "ownership" of a user action pointer, one would expect a region of code that allocates a user action to retain control over when it is to be deleted. So I recommend that the managers NOT delete their user actions. If it is preferred that the managers do gain ownership of their user actions, this should somehow be made explicit (users should not be expected to just "know" this), and there should be a flag allowing one to remove ownership if desired. Actually, the same goes for the detector construction, the physics list, and the primary generator action. This problem caused a segmentation fault for me when I attempted to make a class deriving from both G4UserSteppingAction and G4UserRunAction. I allocated a new instance of this class in my main block, and gave the pointer to the G4RunManager as both a G4UserSteppingAction* and a G4UserRunAction*. The seg fault occured when both the G4SteppingManager and the G4RunManager attempted to delete the same region of memory in their destructors, which I expected to delete myself in main.
It is stated so in the users guide that deleting G4RunManager causes deletion of all user action classes. Also, I do not see any good reason to make a class derived from both RunAction and SteppingAction. If you have a class need to be invoked from both of these action classes, take one of two possible ways. 1) Add a method in your SteppingAction class which can be invoked from your RunAction class. 2) Create a class to be accessed from both of your RunAction and SteppingAction classes. I suggest you to avoid multiple-inheritance.
