[Pse]

ShprotX, those are some good points.

1) I agree, it's not really necessary to create a temporary object, compare, and return accordingly. Either by throwing an exception or by returning what gtk returned, if object construction fails, we'll still end up a with a null object.
2) Yes, it'd be bad if the user bypassed gtkd and then passed the object to gtkd without first checking it. I think this provides a good example of when exceptions might provide good information for unhandled cases.

However, I'd like to address your point about unnecessary memory copies. Object construction should not be considered a cheap operation: resources are being assigned, base class constructors getting called, etc. Therefore, a simple pointer copy operation is virtually free. There's no point trying in trying to optimize them out. However, I do agree they're not really needed (not even for code clarity), so it might be in place to avoid them, as you propose.