pass a delegate to an API as a context pointer?

[teo]

Kirk McDonald Wrote:
> There is a serious problem with this. The garbage collector will not 
> scan the C library for references. As far as it is concerned, that 
> struct on the heap will have no references to it (assuming your program 
> is more interesting than a single main() function, and this callback is 
> being assigned in some function that returns), and it might be 
> collected. Furthermore, if that delegate holds the only reference to 
> that 'A' instance, it might be collected, too.
> 
> You'll need to somehow keep a reference to that struct locally (that is, 
> within your D code).

Is there any way to force the garbage collector to "cleanup", so I can experiment with it and see where  my software breaks? Perhaps I do have some weak references.